* NOTE: Technically, the JPEG format uses the YCbCr colorspace, but per the * convention of the digital video community, the TurboJPEG API uses "YUV" to * refer to an image format consisting of Y, Cb, and Cr image planes. */ enum TJSAMP { /** * 4:4:4 chrominance subsampling (no chrominance subsampling). The JPEG or * YUV image will contain one chrominance component for every pixel in the * source image. */ TJSAMP_444=0, /** * 4:2:2 chrominance subsampling. The JPEG or YUV image will contain one * chrominance component for every 2x1 block of pixels in the source image. */ TJSAMP_422, /** * 4:2:0 chrominance subsampling. The JPEG or YUV image will contain one * chrominance component for every 2x2 block of pixels in the source image. */ TJSAMP_420, /** * Grayscale. The JPEG or YUV image will contain no chrominance components. */ TJSAMP_GRAY, /** * 4:4:0 chrominance subsampling. The JPEG or YUV image will contain one * chrominance component for every 1x2 block of pixels in the source image. * Note that 4:4:0 subsampling is not fully accelerated in libjpeg-turbo. */ TJSAMP_440, /** * 4:1:1 chrominance subsampling. The JPEG or YUV image will contain one * chrominance component for every 4x1 block of pixels in the source image. * JPEG images compressed with 4:1:1 subsampling will be almost exactly the * same size as those compressed with 4:2:0 subsampling, and in the * aggregate, both subsampling methods produce approximately the same * perceptual quality. However, 4:1:1 is better able to reproduce sharp * horizontal features. Note that 4:1:1 subsampling is not fully accelerated * in libjpeg-turbo. */ TJSAMP_411 }; /** * MCU block width (in pixels) for a given level of chrominance subsampling. * MCU block sizes: * - 8x8 for no subsampling or grayscale * - 16x8 for 4:2:2 * - 8x16 for 4:4:0 * - 16x16 for 4:2:0 * - 32x8 for 4:1:1 */ static const int tjMCUWidth[TJ_NUMSAMP] = {8, 16, 16, 8, 8, 32}; /** * MCU block height (in pixels) for a given level of chrominance subsampling. * MCU block sizes: * - 8x8 for no subsampling or grayscale * - 16x8 for 4:2:2 * - 8x16 for 4:4:0 * - 16x16 for 4:2:0 * - 32x8 for 4:1:1 */ static const int tjMCUHeight[TJ_NUMSAMP] = {8, 8, 16, 8, 16, 8}; /** * The number of pixel formats */ #define TJ_NUMPF 12 /** * Pixel formats */ enum TJPF { /** * RGB pixel format. The red, green, and blue components in the image are * stored in 3-byte pixels in the order R, G, B from lowest to highest byte * address within each pixel. */ TJPF_RGB=0, /** * BGR pixel format. The red, green, and blue components in the image are * stored in 3-byte pixels in the order B, G, R from lowest to highest byte * address within each pixel. */ TJPF_BGR, /** * RGBX pixel format. The red, green, and blue components in the image are * stored in 4-byte pixels in the order R, G, B from lowest to highest byte * address within each pixel. The X component is ignored when compressing * and undefined when decompressing. */ TJPF_RGBX, /** * BGRX pixel format. The red, green, and blue components in the image are * stored in 4-byte pixels in the order B, G, R from lowest to highest byte * address within each pixel. The X component is ignored when compressing * and undefined when decompressing. */ TJPF_BGRX, /** * XBGR pixel format. The red, green, and blue components in the image are * stored in 4-byte pixels in the order R, G, B from highest to lowest byte * address within each pixel. The X component is ignored when compressing * and undefined when decompressing. */ TJPF_XBGR, /** * XRGB pixel format. The red, green, and blue components in the image are * stored in 4-byte pixels in the order B, G, R from highest to lowest byte * address within each pixel. The X component is ignored when compressing * and undefined when decompressing. */ TJPF_XRGB, /** * Grayscale pixel format. Each 1-byte pixel represents a luminance * (brightness) level from 0 to 255. */ TJPF_GRAY, /** * RGBA pixel format. This is the same as @ref TJPF_RGBX, except that when * decompressing, the X component is guaranteed to be 0xFF, which can be * interpreted as an opaque alpha channel. */ TJPF_RGBA, /** * BGRA pixel format. This is the same as @ref TJPF_BGRX, except that when * decompressing, the X component is guaranteed to be 0xFF, which can be * interpreted as an opaque alpha channel. */ TJPF_BGRA, /** * ABGR pixel format. This is the same as @ref TJPF_XBGR, except that when * decompressing, the X component is guaranteed to be 0xFF, which can be * interpreted as an opaque alpha channel. */ TJPF_ABGR, /** * ARGB pixel format. This is the same as @ref TJPF_XRGB, except that when * decompressing, the X component is guaranteed to be 0xFF, which can be * interpreted as an opaque alpha channel. */ TJPF_ARGB, /** * CMYK pixel format. Unlike RGB, which is an additive color model used * primarily for display, CMYK (Cyan/Magenta/Yellow/Key) is a subtractive * color model used primarily for printing. In the CMYK color model, the * value of each color component typically corresponds to an amount of cyan, * magenta, yellow, or black ink that is applied to a white background. In * order to convert between CMYK and RGB, it is necessary to use a color * management system (CMS.) A CMS will attempt to map colors within the * printer's gamut to perceptually similar colors in the display's gamut and * vice versa, but the mapping is typically not 1:1 or reversible, nor can it * be defined with a simple formula. Thus, such a conversion is out of scope * for a codec library. However, the TurboJPEG API allows for compressing * CMYK pixels into a YCCK JPEG image (see #TJCS_YCCK) and decompressing YCCK * JPEG images into CMYK pixels. */ TJPF_CMYK }; /** * Red offset (in bytes) for a given pixel format. This specifies the number * of bytes that the red component is offset from the start of the pixel. For * instance, if a pixel of format TJ_BGRX is stored in char pixel[], * then the red component will be pixel[tjRedOffset[TJ_BGRX]]. */ static const int tjRedOffset[TJ_NUMPF] = {0, 2, 0, 2, 3, 1, 0, 0, 2, 3, 1, -1}; /** * Green offset (in bytes) for a given pixel format. This specifies the number * of bytes that the green component is offset from the start of the pixel. * For instance, if a pixel of format TJ_BGRX is stored in * char pixel[], then the green component will be * pixel[tjGreenOffset[TJ_BGRX]]. */ static const int tjGreenOffset[TJ_NUMPF] = {1, 1, 1, 1, 2, 2, 0, 1, 1, 2, 2, -1}; /** * Blue offset (in bytes) for a given pixel format. This specifies the number * of bytes that the Blue component is offset from the start of the pixel. For * instance, if a pixel of format TJ_BGRX is stored in char pixel[], * then the blue component will be pixel[tjBlueOffset[TJ_BGRX]]. */ static const int tjBlueOffset[TJ_NUMPF] = {2, 0, 2, 0, 1, 3, 0, 2, 0, 1, 3, -1}; /** * Pixel size (in bytes) for a given pixel format. */ static const int tjPixelSize[TJ_NUMPF] = {3, 3, 4, 4, 4, 4, 1, 4, 4, 4, 4, 4}; /** * The number of JPEG colorspaces */ #define TJ_NUMCS 5 /** * JPEG colorspaces */ enum TJCS { /** * RGB colorspace. When compressing the JPEG image, the R, G, and B * components in the source image are reordered into image planes, but no * colorspace conversion or subsampling is performed. RGB JPEG images can be * decompressed to any of the extended RGB pixel formats or grayscale, but * they cannot be decompressed to YUV images. */ TJCS_RGB=0, /** * YCbCr colorspace. YCbCr is not an absolute colorspace but rather a * mathematical transformation of RGB designed solely for storage and * transmission. YCbCr images must be converted to RGB before they can * actually be displayed. In the YCbCr colorspace, the Y (luminance) * component represents the black & white portion of the original image, and * the Cb and Cr (chrominance) components represent the color portion of the * original image. Originally, the analog equivalent of this transformation * allowed the same signal to drive both black & white and color televisions, * but JPEG images use YCbCr primarily because it allows the color data to be * optionally subsampled for the purposes of reducing bandwidth or disk * space. YCbCr is the most common JPEG colorspace, and YCbCr JPEG images * can be compressed from and decompressed to any of the extended RGB pixel * formats or grayscale, or they can be decompressed to YUV planar images. */ TJCS_YCbCr, /** * Grayscale colorspace. The JPEG image retains only the luminance data (Y * component), and any color data from the source image is discarded. * Grayscale JPEG images can be compressed from and decompressed to any of * the extended RGB pixel formats or grayscale, or they can be decompressed * to YUV planar images. */ TJCS_GRAY, /** * CMYK colorspace. When compressing the JPEG image, the C, M, Y, and K * components in the source image are reordered into image planes, but no * colorspace conversion or subsampling is performed. CMYK JPEG images can * only be decompressed to CMYK pixels. */ TJCS_CMYK, /** * YCCK colorspace. YCCK (AKA "YCbCrK") is not an absolute colorspace but * rather a mathematical transformation of CMYK designed solely for storage * and transmission. It is to CMYK as YCbCr is to RGB. CMYK pixels can be * reversibly transformed into YCCK, and as with YCbCr, the chrominance * components in the YCCK pixels can be subsampled without incurring major * perceptual loss. YCCK JPEG images can only be compressed from and * decompressed to CMYK pixels. */ TJCS_YCCK }; /** * The uncompressed source/destination image is stored in bottom-up (Windows, * OpenGL) order, not top-down (X11) order. */ #define TJFLAG_BOTTOMUP 2 /** * When decompressing an image that was compressed using chrominance * subsampling, use the fastest chrominance upsampling algorithm available in * the underlying codec. The default is to use smooth upsampling, which * creates a smooth transition between neighboring chrominance components in * order to reduce upsampling artifacts in the decompressed image. */ #define TJFLAG_FASTUPSAMPLE 256 /** * Disable buffer (re)allocation. If passed to #tjCompress2() or * #tjTransform(), this flag will cause those functions to generate an error if * the JPEG image buffer is invalid or too small rather than attempting to * allocate or reallocate that buffer. This reproduces the behavior of earlier * versions of TurboJPEG. */ #define TJFLAG_NOREALLOC 1024 /** * Use the fastest DCT/IDCT algorithm available in the underlying codec. The * default if this flag is not specified is implementation-specific. For * example, the implementation of TurboJPEG for libjpeg[-turbo] uses the fast * algorithm by default when compressing, because this has been shown to have * only a very slight effect on accuracy, but it uses the accurate algorithm * when decompressing, because this has been shown to have a larger effect. */ #define TJFLAG_FASTDCT 2048 /** * Use the most accurate DCT/IDCT algorithm available in the underlying codec. * The default if this flag is not specified is implementation-specific. For * example, the implementation of TurboJPEG for libjpeg[-turbo] uses the fast * algorithm by default when compressing, because this has been shown to have * only a very slight effect on accuracy, but it uses the accurate algorithm * when decompressing, because this has been shown to have a larger effect. */ #define TJFLAG_ACCURATEDCT 4096 /** * The number of transform operations */ #define TJ_NUMXOP 8 /** * Transform operations for #tjTransform() */ enum TJXOP { /** * Do not transform the position of the image pixels */ TJXOP_NONE=0, /** * Flip (mirror) image horizontally. This transform is imperfect if there * are any partial MCU blocks on the right edge (see #TJXOPT_PERFECT.) */ TJXOP_HFLIP, /** * Flip (mirror) image vertically. This transform is imperfect if there are * any partial MCU blocks on the bottom edge (see #TJXOPT_PERFECT.) */ TJXOP_VFLIP, /** * Transpose image (flip/mirror along upper left to lower right axis.) This * transform is always perfect. */ TJXOP_TRANSPOSE, /** * Transverse transpose image (flip/mirror along upper right to lower left * axis.) This transform is imperfect if there are any partial MCU blocks in * the image (see #TJXOPT_PERFECT.) */ TJXOP_TRANSVERSE, /** * Rotate image clockwise by 90 degrees. This transform is imperfect if * there are any partial MCU blocks on the bottom edge (see * #TJXOPT_PERFECT.) */ TJXOP_ROT90, /** * Rotate image 180 degrees. This transform is imperfect if there are any * partial MCU blocks in the image (see #TJXOPT_PERFECT.) */ TJXOP_ROT180, /** * Rotate image counter-clockwise by 90 degrees. This transform is imperfect * if there are any partial MCU blocks on the right edge (see * #TJXOPT_PERFECT.) */ TJXOP_ROT270 }; /** * This option will cause #tjTransform() to return an error if the transform is * not perfect. Lossless transforms operate on MCU blocks, whose size depends * on the level of chrominance subsampling used (see #tjMCUWidth * and #tjMCUHeight.) If the image's width or height is not evenly divisible * by the MCU block size, then there will be partial MCU blocks on the right * and/or bottom edges. It is not possible to move these partial MCU blocks to * the top or left of the image, so any transform that would require that is * "imperfect." If this option is not specified, then any partial MCU blocks * that cannot be transformed will be left in place, which will create * odd-looking strips on the right or bottom edge of the image. */ #define TJXOPT_PERFECT 1 /** * This option will cause #tjTransform() to discard any partial MCU blocks that * cannot be transformed. */ #define TJXOPT_TRIM 2 /** * This option will enable lossless cropping. See #tjTransform() for more * information. */ #define TJXOPT_CROP 4 /** * This option will discard the color data in the input image and produce * a grayscale output image. */ #define TJXOPT_GRAY 8 /** * This option will prevent #tjTransform() from outputting a JPEG image for * this particular transform (this can be used in conjunction with a custom * filter to capture the transformed DCT coefficients without transcoding * them.) */ #define TJXOPT_NOOUTPUT 16 /** * Scaling factor */ typedef struct { /** * Numerator */ int num; /** * Denominator */ int denom; } tjscalingfactor; /** * Cropping region */ typedef struct { /** * The left boundary of the cropping region. This must be evenly divisible * by the MCU block width (see #tjMCUWidth.) */ int x; /** * The upper boundary of the cropping region. This must be evenly divisible * by the MCU block height (see #tjMCUHeight.) */ int y; /** * The width of the cropping region. Setting this to 0 is the equivalent of * setting it to the width of the source JPEG image - x. */ int w; /** * The height of the cropping region. Setting this to 0 is the equivalent of * setting it to the height of the source JPEG image - y. */ int h; } tjregion; /** * Lossless transform */ typedef struct tjtransform { /** * Cropping region */ tjregion r; /** * One of the @ref TJXOP "transform operations" */ int op; /** * The bitwise OR of one of more of the @ref TJXOPT_CROP "transform options" */ int options; /** * Arbitrary data that can be accessed within the body of the callback * function */ void *data; /** * A callback function that can be used to modify the DCT coefficients * after they are losslessly transformed but before they are transcoded to a * new JPEG image. This allows for custom filters or other transformations * to be applied in the frequency domain. * * @param coeffs pointer to an array of transformed DCT coefficients. (NOTE: * this pointer is not guaranteed to be valid once the callback * returns, so applications wishing to hand off the DCT coefficients * to another function or library should make a copy of them within * the body of the callback.) * @param arrayRegion #tjregion structure containing the width and height of * the array pointed to by coeffs as well as its offset * relative to the component plane. TurboJPEG implementations may * choose to split each component plane into multiple DCT coefficient * arrays and call the callback function once for each array. * @param planeRegion #tjregion structure containing the width and height of * the component plane to which coeffs belongs * @param componentID ID number of the component plane to which * coeffs belongs (Y, Cb, and Cr have, respectively, ID's of * 0, 1, and 2 in typical JPEG images.) * @param transformID ID number of the transformed image to which * coeffs belongs. This is the same as the index of the * transform in the transforms array that was passed to * #tjTransform(). * @param transform a pointer to a #tjtransform structure that specifies the * parameters and/or cropping region for this transform * * @return 0 if the callback was successful, or -1 if an error occurred. */ int (*customFilter)(short *coeffs, tjregion arrayRegion, tjregion planeRegion, int componentIndex, int transformIndex, struct tjtransform *transform); } tjtransform; /** * TurboJPEG instance handle */ typedef void* tjhandle; /** * Pad the given width to the nearest 32-bit boundary */ #define TJPAD(width) (((width)+3)&(~3)) /** * Compute the scaled value of dimension using the given scaling * factor. This macro performs the integer equivalent of ceil(dimension * * scalingFactor). */ #define TJSCALED(dimension, scalingFactor) ((dimension * scalingFactor.num \ + scalingFactor.denom - 1) / scalingFactor.denom) #ifdef __cplusplus extern "C" { #endif /** * Create a TurboJPEG compressor instance. * * @return a handle to the newly-created instance, or NULL if an error * occurred (see #tjGetErrorStr().) */ DLLEXPORT tjhandle DLLCALL tjInitCompress(void); /** * Compress an RGB, grayscale, or CMYK image into a JPEG image. * * @param handle a handle to a TurboJPEG compressor or transformer instance * @param srcBuf pointer to an image buffer containing RGB, grayscale, or * CMYK pixels to be compressed * @param width width (in pixels) of the source image * @param pitch bytes per line of the source image. Normally, this should be * width * #tjPixelSize[pixelFormat] if the image is unpadded, * or #TJPAD(width * #tjPixelSize[pixelFormat]) if each line of * the image is padded to the nearest 32-bit boundary, as is the case * for Windows bitmaps. You can also be clever and use this parameter * to skip lines, etc. Setting this parameter to 0 is the equivalent of * setting it to width * #tjPixelSize[pixelFormat]. * @param height height (in pixels) of the source image * @param pixelFormat pixel format of the source image (see @ref TJPF * "Pixel formats".) * @param jpegBuf address of a pointer to an image buffer that will receive the * JPEG image. TurboJPEG has the ability to reallocate the JPEG buffer * to accommodate the size of the JPEG image. Thus, you can choose to: * -# pre-allocate the JPEG buffer with an arbitrary size using * #tjAlloc() and let TurboJPEG grow the buffer as needed, * -# set *jpegBuf to NULL to tell TurboJPEG to allocate the * buffer for you, or * -# pre-allocate the buffer to a "worst case" size determined by * calling #tjBufSize(). This should ensure that the buffer never has * to be re-allocated (setting #TJFLAG_NOREALLOC guarantees this.) * . * If you choose option 1, *jpegSize should be set to the * size of your pre-allocated buffer. In any case, unless you have * set #TJFLAG_NOREALLOC, you should always check *jpegBuf upon * return from this function, as it may have changed. * @param jpegSize pointer to an unsigned long variable that holds the size of * the JPEG image buffer. If *jpegBuf points to a * pre-allocated buffer, then *jpegSize should be set to the * size of the buffer. Upon return, *jpegSize will contain the * size of the JPEG image (in bytes.) * @param jpegSubsamp the level of chrominance subsampling to be used when * generating the JPEG image (see @ref TJSAMP * "Chrominance subsampling options".) * @param jpegQual the image quality of the generated JPEG image (1 = worst, 100 = best) * @param flags the bitwise OR of one or more of the @ref TJFLAG_BOTTOMUP * "flags". * * @return 0 if successful, or -1 if an error occurred (see #tjGetErrorStr().) */ DLLEXPORT int DLLCALL tjCompress2(tjhandle handle, unsigned char *srcBuf, int width, int pitch, int height, int pixelFormat, unsigned char **jpegBuf, unsigned long *jpegSize, int jpegSubsamp, int jpegQual, int flags); /** * Compress a YUV planar image into a JPEG image. * * @param handle a handle to a TurboJPEG compressor or transformer instance * @param srcBuf pointer to an image buffer containing a YUV planar image * to be compressed. The Y, U (Cb), and V (Cr) image planes should be * stored sequentially in the buffer, and the size of each plane * is determined by the specified width, height, padding, and level of * chrominance subsampling. If the chrominance components are * subsampled along the horizontal dimension, then the width of the * luminance plane should be padded to the nearest multiple of 2 (same * goes for the height of the luminance plane, if the chrominance * components are subsampled along the vertical dimension.) This is * irrespective of any additional padding specified in the pad * parameter. * @param width width (in pixels) of the source image * @param pad the line padding used in the source image. For instance, if each * line in each plane of the YUV image is padded to the nearest multiple * of 4 bytes, then pad should be set to 4. * @param height height (in pixels) of the source image * @param subsamp the level of chrominance subsampling used in the source * image (see @ref TJSAMP "Chrominance subsampling options".) * @param jpegBuf address of a pointer to an image buffer that will receive the * JPEG image. TurboJPEG has the ability to reallocate the JPEG buffer * to accommodate the size of the JPEG image. Thus, you can choose to: * -# pre-allocate the JPEG buffer with an arbitrary size using * #tjAlloc() and let TurboJPEG grow the buffer as needed, * -# set *jpegBuf to NULL to tell TurboJPEG to allocate the * buffer for you, or * -# pre-allocate the buffer to a "worst case" size determined by * calling #tjBufSize(). This should ensure that the buffer never has * to be re-allocated (setting #TJFLAG_NOREALLOC guarantees this.) * . * If you choose option 1, *jpegSize should be set to the * size of your pre-allocated buffer. In any case, unless you have * set #TJFLAG_NOREALLOC, you should always check *jpegBuf upon * return from this function, as it may have changed. * @param jpegSize pointer to an unsigned long variable that holds the size of * the JPEG image buffer. If *jpegBuf points to a * pre-allocated buffer, then *jpegSize should be set to the * size of the buffer. Upon return, *jpegSize will contain the * size of the JPEG image (in bytes.) * @param jpegQual the image quality of the generated JPEG image (1 = worst, 100 = best) * @param flags the bitwise OR of one or more of the @ref TJFLAG_BOTTOMUP * "flags". * * @return 0 if successful, or -1 if an error occurred (see #tjGetErrorStr().) */ DLLEXPORT int DLLCALL tjCompressFromYUV(tjhandle handle, unsigned char *srcBuf, int width, int pad, int height, int subsamp, unsigned char **jpegBuf, unsigned long *jpegSize, int jpegQual, int flags); /** * The maximum size of the buffer (in bytes) required to hold a JPEG image with * the given parameters. The number of bytes returned by this function is * larger than the size of the uncompressed source image. The reason for this * is that the JPEG format uses 16-bit coefficients, and it is thus possible * for a very high-quality JPEG image with very high-frequency content to * expand rather than compress when converted to the JPEG format. Such images * represent a very rare corner case, but since there is no way to predict the * size of a JPEG image prior to compression, the corner case has to be * handled. * * @param width width of the image (in pixels) * @param height height of the image (in pixels) * @param jpegSubsamp the level of chrominance subsampling to be used when * generating the JPEG image (see @ref TJSAMP * "Chrominance subsampling options".) * * @return the maximum size of the buffer (in bytes) required to hold the * image, or -1 if the arguments are out of bounds. */ DLLEXPORT unsigned long DLLCALL tjBufSize(int width, int height, int jpegSubsamp); /** * The size of the buffer (in bytes) required to hold a YUV planar image with * the given parameters. * * @param width width of the image (in pixels) * @param pad the width of each line in each plane of the image is padded to * the nearest multiple of this number of bytes (must be a power of 2.) * @param height height of the image (in pixels) * @param subsamp level of chrominance subsampling in the image (see * @ref TJSAMP "Chrominance subsampling options".) * * @return the size of the buffer (in bytes) required to hold the image, or * -1 if the arguments are out of bounds. */ DLLEXPORT unsigned long DLLCALL tjBufSizeYUV2(int width, int pad, int height, int subsamp); /** * Encode an RGB or grayscale image into a YUV planar image. This function * uses the accelerated color conversion routines in TurboJPEG's underlying * codec but does not execute any of the other steps in the JPEG compression * process. The Y, U (Cb), and V (Cr) image planes are stored sequentially * into the destination buffer, and the size of each plane is determined by the * width and height of the source image, as well as the specified padding and * level of chrominance subsampling. If the chrominance components are * subsampled along the horizontal dimension, then the width of the luminance * plane is padded to the nearest multiple of 2 in the output image (same goes * for the height of the luminance plane, if the chrominance components are * subsampled along the vertical dimension.) *
* NOTE: Technically, the JPEG format uses the YCbCr colorspace, but per the * convention of the digital video community, the TurboJPEG API uses "YUV" to * refer to an image format consisting of Y, Cb, and Cr image planes. * * @param handle a handle to a TurboJPEG compressor or transformer instance * @param srcBuf pointer to an image buffer containing RGB or grayscale pixels * to be encoded * @param width width (in pixels) of the source image * @param pitch bytes per line of the source image. Normally, this should be * width * #tjPixelSize[pixelFormat] if the image is unpadded, * or #TJPAD(width * #tjPixelSize[pixelFormat]) if each line of * the image is padded to the nearest 32-bit boundary, as is the case * for Windows bitmaps. You can also be clever and use this parameter * to skip lines, etc. Setting this parameter to 0 is the equivalent of * setting it to width * #tjPixelSize[pixelFormat]. * @param height height (in pixels) of the source image * @param pixelFormat pixel format of the source image (see @ref TJPF * "Pixel formats".) * @param dstBuf pointer to an image buffer that will receive the YUV image. * Use #tjBufSizeYUV2() to determine the appropriate size for this * buffer based on the image width, height, padding, and level of * chrominance subsampling. * @param pad the width of each line in each plane of the YUV image will be * padded to the nearest multiple of this number of bytes (must be a * power of 2.) To generate images suitable for X Video, pad * should be set to 4. * @param subsamp the level of chrominance subsampling to be used when * generating the YUV image (see @ref TJSAMP * "Chrominance subsampling options".) To generate images suitable for * X Video, subsamp should be set to @ref TJSAMP_420. This * produces an image compatible with the I420 (AKA "YUV420P") format. * @param flags the bitwise OR of one or more of the @ref TJFLAG_BOTTOMUP * "flags". * * @return 0 if successful, or -1 if an error occurred (see #tjGetErrorStr().) */ DLLEXPORT int DLLCALL tjEncodeYUV3(tjhandle handle, unsigned char *srcBuf, int width, int pitch, int height, int pixelFormat, unsigned char *dstBuf, int pad, int subsamp, int flags); /** * Create a TurboJPEG decompressor instance. * * @return a handle to the newly-created instance, or NULL if an error * occurred (see #tjGetErrorStr().) */ DLLEXPORT tjhandle DLLCALL tjInitDecompress(void); /** * Retrieve information about a JPEG image without decompressing it. * * @param handle a handle to a TurboJPEG decompressor or transformer instance * @param jpegBuf pointer to a buffer containing a JPEG image * @param jpegSize size of the JPEG image (in bytes) * @param width pointer to an integer variable that will receive the width (in * pixels) of the JPEG image * @param height pointer to an integer variable that will receive the height * (in pixels) of the JPEG image * @param jpegSubsamp pointer to an integer variable that will receive the * level of chrominance subsampling used when compressing the JPEG image * (see @ref TJSAMP "Chrominance subsampling options".) * @param jpegColorspace pointer to an integer variable that will receive one * of the JPEG colorspace constants, indicating the colorspace of the * JPEG image (see @ref TJCS "JPEG colorspaces".) * * @return 0 if successful, or -1 if an error occurred (see #tjGetErrorStr().) */ DLLEXPORT int DLLCALL tjDecompressHeader3(tjhandle handle, unsigned char *jpegBuf, unsigned long jpegSize, int *width, int *height, int *jpegSubsamp, int *jpegColorspace); /** * Returns a list of fractional scaling factors that the JPEG decompressor in * this implementation of TurboJPEG supports. * * @param numscalingfactors pointer to an integer variable that will receive * the number of elements in the list * * @return a pointer to a list of fractional scaling factors, or NULL if an * error is encountered (see #tjGetErrorStr().) */ DLLEXPORT tjscalingfactor* DLLCALL tjGetScalingFactors(int *numscalingfactors); /** * Decompress a JPEG image to an RGB, grayscale, or CMYK image. * * @param handle a handle to a TurboJPEG decompressor or transformer instance * @param jpegBuf pointer to a buffer containing the JPEG image to decompress * @param jpegSize size of the JPEG image (in bytes) * @param dstBuf pointer to an image buffer that will receive the decompressed * image. This buffer should normally be pitch * scaledHeight * bytes in size, where scaledHeight can be determined by * calling #TJSCALED() with the JPEG image height and one of the scaling * factors returned by #tjGetScalingFactors(). The dstBuf * pointer may also be used to decompress into a specific region of a * larger buffer. * @param width desired width (in pixels) of the destination image. If this is * different than the width of the JPEG image being decompressed, then * TurboJPEG will use scaling in the JPEG decompressor to generate the * largest possible image that will fit within the desired width. If * width is set to 0, then only the height will be considered * when determining the scaled image size. * @param pitch bytes per line of the destination image. Normally, this is * scaledWidth * #tjPixelSize[pixelFormat] if the decompressed * image is unpadded, else #TJPAD(scaledWidth * * #tjPixelSize[pixelFormat]) if each line of the decompressed * image is padded to the nearest 32-bit boundary, as is the case for * Windows bitmaps. (NOTE: scaledWidth can be determined by * calling #TJSCALED() with the JPEG image width and one of the scaling * factors returned by #tjGetScalingFactors().) You can also be clever * and use the pitch parameter to skip lines, etc. Setting this * parameter to 0 is the equivalent of setting it to * scaledWidth * #tjPixelSize[pixelFormat]. * @param height desired height (in pixels) of the destination image. If this * is different than the height of the JPEG image being decompressed, * then TurboJPEG will use scaling in the JPEG decompressor to generate * the largest possible image that will fit within the desired height. * If height is set to 0, then only the width will be * considered when determining the scaled image size. * @param pixelFormat pixel format of the destination image (see @ref * TJPF "Pixel formats".) * @param flags the bitwise OR of one or more of the @ref TJFLAG_BOTTOMUP * "flags". * * @return 0 if successful, or -1 if an error occurred (see #tjGetErrorStr().) */ DLLEXPORT int DLLCALL tjDecompress2(tjhandle handle, unsigned char *jpegBuf, unsigned long jpegSize, unsigned char *dstBuf, int width, int pitch, int height, int pixelFormat, int flags); /** * Decompress a JPEG image to a YUV planar image. This function performs JPEG * decompression but leaves out the color conversion step, so a planar YUV * image is generated instead of an RGB image. The structure of the planes in * this image is the same as in the images generated by #tjEncodeYUV3(). Note * that, if the width or height of the JPEG image is not an even multiple of * the MCU block size (see #tjMCUWidth and #tjMCUHeight), then an intermediate * buffer copy will be performed within TurboJPEG. *
* NOTE: Technically, the JPEG format uses the YCbCr colorspace, but per the * convention of the digital video community, the TurboJPEG API uses "YUV" to * refer to an image format consisting of Y, Cb, and Cr image planes. * * @param handle a handle to a TurboJPEG decompressor or transformer instance * @param jpegBuf pointer to a buffer containing the JPEG image to decompress * @param jpegSize size of the JPEG image (in bytes) * @param dstBuf pointer to an image buffer that will receive the YUV image. * Use #tjBufSizeYUV2() to determine the appropriate size for this * buffer based on the image width, height, padding, and level of * subsampling. * @param width desired width (in pixels) of the YUV image. If this is * different than the width of the JPEG image being decompressed, then * TurboJPEG will use scaling in the JPEG decompressor to generate the * largest possible image that will fit within the desired width. If * width is set to 0, then only the height will be considered * when determining the scaled image size. * @param pad the width of each line in each plane of the YUV image will be * padded to the nearest multiple of this number of bytes (must be a * power of 2.) To generate images suitable for X Video, pad * should be set to 4. * @param height desired height (in pixels) of the YUV image. If this is * different than the height of the JPEG image being decompressed, then * TurboJPEG will use scaling in the JPEG decompressor to generate the * largest possible image that will fit within the desired height. If * height is set to 0, then only the width will be considered * when determining the scaled image size. * @param flags the bitwise OR of one or more of the @ref TJFLAG_BOTTOMUP * "flags". * * @return 0 if successful, or -1 if an error occurred (see #tjGetErrorStr().) */ DLLEXPORT int DLLCALL tjDecompressToYUV2(tjhandle handle, unsigned char *jpegBuf, unsigned long jpegSize, unsigned char *dstBuf, int width, int pad, int height, int flags); /** * Create a new TurboJPEG transformer instance. * * @return a handle to the newly-created instance, or NULL if an error * occurred (see #tjGetErrorStr().) */ DLLEXPORT tjhandle DLLCALL tjInitTransform(void); /** * Losslessly transform a JPEG image into another JPEG image. Lossless * transforms work by moving the raw coefficients from one JPEG image structure * to another without altering the values of the coefficients. While this is * typically faster than decompressing the image, transforming it, and * re-compressing it, lossless transforms are not free. Each lossless * transform requires reading and performing Huffman decoding on all of the * coefficients in the source image, regardless of the size of the destination * image. Thus, this function provides a means of generating multiple * transformed images from the same source or applying multiple * transformations simultaneously, in order to eliminate the need to read the * source coefficients multiple times. * * @param handle a handle to a TurboJPEG transformer instance * @param jpegBuf pointer to a buffer containing the JPEG image to transform * @param jpegSize size of the JPEG image (in bytes) * @param n the number of transformed JPEG images to generate * @param dstBufs pointer to an array of n image buffers. dstBufs[i] * will receive a JPEG image that has been transformed using the * parameters in transforms[i]. TurboJPEG has the ability to * reallocate the JPEG buffer to accommodate the size of the JPEG image. * Thus, you can choose to: * -# pre-allocate the JPEG buffer with an arbitrary size using * #tjAlloc() and let TurboJPEG grow the buffer as needed, * -# set dstBufs[i] to NULL to tell TurboJPEG to allocate the * buffer for you, or * -# pre-allocate the buffer to a "worst case" size determined by * calling #tjBufSize() with the transformed or cropped width and * height. This should ensure that the buffer never has to be * re-allocated (setting #TJFLAG_NOREALLOC guarantees this.) * . * If you choose option 1, dstSizes[i] should be set to * the size of your pre-allocated buffer. In any case, unless you have * set #TJFLAG_NOREALLOC, you should always check dstBufs[i] * upon return from this function, as it may have changed. * @param dstSizes pointer to an array of n unsigned long variables that will * receive the actual sizes (in bytes) of each transformed JPEG image. * If dstBufs[i] points to a pre-allocated buffer, then * dstSizes[i] should be set to the size of the buffer. Upon * return, dstSizes[i] will contain the size of the JPEG image * (in bytes.) * @param transforms pointer to an array of n #tjtransform structures, each of * which specifies the transform parameters and/or cropping region for * the corresponding transformed output image. * @param flags the bitwise OR of one or more of the @ref TJFLAG_BOTTOMUP * "flags". * * @return 0 if successful, or -1 if an error occurred (see #tjGetErrorStr().) */ DLLEXPORT int DLLCALL tjTransform(tjhandle handle, unsigned char *jpegBuf, unsigned long jpegSize, int n, unsigned char **dstBufs, unsigned long *dstSizes, tjtransform *transforms, int flags); /** * Destroy a TurboJPEG compressor, decompressor, or transformer instance. * * @param handle a handle to a TurboJPEG compressor, decompressor or * transformer instance * * @return 0 if successful, or -1 if an error occurred (see #tjGetErrorStr().) */ DLLEXPORT int DLLCALL tjDestroy(tjhandle handle); /** * Allocate an image buffer for use with TurboJPEG. You should always use * this function to allocate the JPEG destination buffer(s) for #tjCompress2() * and #tjTransform() unless you are disabling automatic buffer * (re)allocation (by setting #TJFLAG_NOREALLOC.) * * @param bytes the number of bytes to allocate * * @return a pointer to a newly-allocated buffer with the specified number of * bytes * * @sa tjFree() */ DLLEXPORT unsigned char* DLLCALL tjAlloc(int bytes); /** * Free an image buffer previously allocated by TurboJPEG. You should always * use this function to free JPEG destination buffer(s) that were automatically * (re)allocated by #tjCompress2() or #tjTransform() or that were manually * allocated using #tjAlloc(). * * @param buffer address of the buffer to free * * @sa tjAlloc() */ DLLEXPORT void DLLCALL tjFree(unsigned char *buffer); /** * Returns a descriptive error message explaining why the last command failed. * * @return a descriptive error message explaining why the last command failed. */ DLLEXPORT char* DLLCALL tjGetErrorStr(void); /* Deprecated functions and macros */ #define TJFLAG_FORCEMMX 8 #define TJFLAG_FORCESSE 16 #define TJFLAG_FORCESSE2 32 #define TJFLAG_FORCESSE3 128 /* Backward compatibility functions and macros (nothing to see here) */ #define NUMSUBOPT TJ_NUMSAMP #define TJ_444 TJSAMP_444 #define TJ_422 TJSAMP_422 #define TJ_420 TJSAMP_420 #define TJ_411 TJSAMP_420 #define TJ_GRAYSCALE TJSAMP_GRAY #define TJ_BGR 1 #define TJ_BOTTOMUP TJFLAG_BOTTOMUP #define TJ_FORCEMMX TJFLAG_FORCEMMX #define TJ_FORCESSE TJFLAG_FORCESSE #define TJ_FORCESSE2 TJFLAG_FORCESSE2 #define TJ_ALPHAFIRST 64 #define TJ_FORCESSE3 TJFLAG_FORCESSE3 #define TJ_FASTUPSAMPLE TJFLAG_FASTUPSAMPLE #define TJ_YUV 512 DLLEXPORT unsigned long DLLCALL TJBUFSIZE(int width, int height); DLLEXPORT unsigned long DLLCALL TJBUFSIZEYUV(int width, int height, int jpegSubsamp); DLLEXPORT unsigned long DLLCALL tjBufSizeYUV(int width, int height, int subsamp); DLLEXPORT int DLLCALL tjCompress(tjhandle handle, unsigned char *srcBuf, int width, int pitch, int height, int pixelSize, unsigned char *dstBuf, unsigned long *compressedSize, int jpegSubsamp, int jpegQual, int flags); DLLEXPORT int DLLCALL tjEncodeYUV(tjhandle handle, unsigned char *srcBuf, int width, int pitch, int height, int pixelSize, unsigned char *dstBuf, int subsamp, int flags); DLLEXPORT int DLLCALL tjEncodeYUV2(tjhandle handle, unsigned char *srcBuf, int width, int pitch, int height, int pixelFormat, unsigned char *dstBuf, int subsamp, int flags); DLLEXPORT int DLLCALL tjDecompressHeader(tjhandle handle, unsigned char *jpegBuf, unsigned long jpegSize, int *width, int *height); DLLEXPORT int DLLCALL tjDecompressHeader2(tjhandle handle, unsigned char *jpegBuf, unsigned long jpegSize, int *width, int *height, int *jpegSubsamp); DLLEXPORT int DLLCALL tjDecompress(tjhandle handle, unsigned char *jpegBuf, unsigned long jpegSize, unsigned char *dstBuf, int width, int pitch, int height, int pixelSize, int flags); DLLEXPORT int DLLCALL tjDecompressToYUV(tjhandle handle, unsigned char *jpegBuf, unsigned long jpegSize, unsigned char *dstBuf, int flags); /** * @} */ #ifdef __cplusplus } #endif #endif