ryan/mozjpeg
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

TurboJPEG: Implement 4:4:1 chrominance subsampling

Browse Source 
This allows losslessly transposed or rotated 4:1:1 JPEG images to be
losslessly cropped, partially decompressed, or decompressed to planar
YUV images.

Because tj3Transform() allows multiple lossless transformations to be
chained together, all subsampling options need to have a corresponding
transposed subsampling option.  (This is why 4:4:0 was originally
implemented as well.)  Otherwise, the documentation would be technically
incorrect.  It says that images with unknown subsampling types cannot be
losslessly cropped, partially decompressed, or decompressed to planar
YUV images, but it doesn't say anything about images with known
subsampling types whose subsampling type becomes unknown if the image is
rotated or transposed.  This is one of those situations in which it is
easier to implement a feature that works around the problem than to
document the problem.

Closes #659
This commit is contained in:
DRC
2023-03-09 20:55:43 -06:00
parent 58a3427ffc
commit fc881ebb21
42 changed files with 335 additions and 229 deletions
Download Patch File Download Diff File Expand all files Collapse all files

20
java/org/libjpegturbo/turbojpeg/YUVImage.java
View File

@@ -48,16 +48,16 @@ package org.libjpegturbo.turbojpeg;
* image. The width and height of each plane are determined by the image
* width, height, and level of chrominance subsampling. The luminance plane
* width is the image width padded to the nearest multiple of the horizontal
* subsampling factor (1 in the case of 4:4:4, grayscale, or 4:4:0; 2 in the
* case of 4:2:2 or 4:2:0; 4 in the case of 4:1:1.) Similarly, the luminance
* plane height is the image height padded to the nearest multiple of the
* vertical subsampling factor (1 in the case of 4:4:4, 4:2:2, grayscale, or
* 4:1:1; 2 in the case of 4:2:0 or 4:4:0.) This is irrespective of any
* additional padding that may be specified as an argument to the various
* YUVImage methods. The chrominance plane width is equal to the luminance
* plane width divided by the horizontal subsampling factor, and the
* chrominance plane height is equal to the luminance plane height divided by
* the vertical subsampling factor.
* subsampling factor (1 in the case of 4:4:4, grayscale, 4:4:0, or 4:4:1; 2 in
* the case of 4:2:2 or 4:2:0; 4 in the case of 4:1:1.) Similarly, the
* luminance plane height is the image height padded to the nearest multiple of
* the vertical subsampling factor (1 in the case of 4:4:4, 4:2:2, grayscale,
* or 4:1:1; 2 in the case of 4:2:0 or 4:4:0; 4 in the case of 4:4:1.) This is
* irrespective of any additional padding that may be specified as an argument
* to the various YUVImage methods. The chrominance plane width is equal to
* the luminance plane width divided by the horizontal subsampling factor, and
* the chrominance plane height is equal to the luminance plane height divided
* by the vertical subsampling factor.
* <p>
* For example, if the source image is 35 x 35 pixels and 4:2:2 subsampling is
* used, then the luminance plane would be 36 x 35 bytes, and each of the