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DRC
2011-03-15 19:33:43 +00:00
parent 4a0cf492f4
commit 4c5eae3bd0
1 changed files with 17 additions and 15 deletions
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32
turbojpeg.h
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@@ -84,9 +84,9 @@ TJXFORM_VFLIP, /* Flip (mirror) image vertically. This transform is
bottom edge. */ bottom edge. */
TJXFORM_TRANSPOSE, /* Transpose image (flip/mirror along upper left to lower TJXFORM_TRANSPOSE, /* Transpose image (flip/mirror along upper left to lower
right axis.) This transform is always perfect. */ right axis.) This transform is always perfect. */
TJXFORM_TRANSVERSE, /* Transpose image (flip/mirror along upper right to lower TJXFORM_TRANSVERSE, /* Transverse transpose image (flip/mirror along upper
left axis.) This transform is imperfect if there are right to lower left axis.) This transform is imperfect
any partial MCU blocks in the image. */ if there are any partial MCU blocks in the image. */
TJXFORM_ROT90, /* Rotate image clockwise by 90 degrees. This transform TJXFORM_ROT90, /* Rotate image clockwise by 90 degrees. This transform
is imperfect if there are any partial MCU blocks on the is imperfect if there are any partial MCU blocks on the
bottom edge. */ bottom edge. */
@@ -184,19 +184,21 @@ DLLEXPORT tjhandle DLLCALL tjInitCompress(void);
bytes) of the JPEG image bytes) of the JPEG image
[INPUT] jpegsubsamp = Specifies the level of chrominance subsampling. When [INPUT] jpegsubsamp = Specifies the level of chrominance subsampling. When
the image is converted from the RGB to YCbCr colorspace as part of the the image is converted from the RGB to YCbCr colorspace as part of the
JPEG compression process, every other Cb and Cr (chrominance) pixel can be JPEG compression process, some of the Cb and Cr (chrominance) components
discarded to produce a smaller image with little perceptible loss of image can be discarded or averaged together to produce a smaller image with
clarity (the human eye is more sensitive to small changes in brightness little perceptible loss of image clarity (the human eye is more sensitive
than small changes in color.) to small changes in brightness than small changes in color.)
TJ_420: 4:2:0 subsampling. Discards every other Cb, Cr pixel in both TJ_420: 4:2:0 subsampling. The JPEG image will contain one chrominance
horizontal and vertical directions component for every 2x2 block of pixels in the source image.
TJ_422: 4:2:2 subsampling. Discards every other Cb, Cr pixel only in TJ_422: 4:2:2 subsampling. The JPEG image will contain one chrominance
the horizontal direction component for every 2x1 block of pixels in the source image.
TJ_440: 4:4:0 subsampling. Discards every other Cb, Cr pixel only in TJ_440: 4:4:0 subsampling. The JPEG image will contain one chrominance
the vertical direction component for every 1x2 block of pixels in the source image.
TJ_444: no subsampling TJ_444: no subsampling. The JPEG image will contain one chrominance
TJ_GRAYSCALE: Generate grayscale JPEG image component for every pixel in the source image.
TJ_GRAYSCALE: Generate grayscale JPEG image. The JPEG image will contain
no chrominance components.
[INPUT] jpegqual = JPEG quality (an integer between 0 and 100 inclusive) [INPUT] jpegqual = JPEG quality (an integer between 0 and 100 inclusive)
[INPUT] flags = the bitwise OR of one or more of the flags described in the [INPUT] flags = the bitwise OR of one or more of the flags described in the