Save JPEG without chroma subsampling
Posted: Sun Mar 27, 2016 12:52 am
I've noticed that JPEGs saved with PB library having the same defect as many other regular jpeg libs and image viewers are producing -- noticeable loss of color saturation that affects bright colors. This makes them "dirty" and thus corrupting whole photo/image a lot regardless of quality setting.
That's all result of subsampling applied. https://en.wikipedia.org/wiki/Chroma_subsampling
Here is an image showing the difference between nicely-done JPEG saving lib and one using default noob way:
The typical and easiest solution is to disable chroma subsampling by setting it's block size to 1x1 pixel, so it does bare calculations and not affects image pixels.
There is big sense to do this, as it surely increases size of JPEG files slightly, but they anyway are taking much less space than PNG or any true lossless format. Thus cool quality/size coefficient is provided to store all your precious photos.
I suggest to add such fix to PB library and some kind of flag to use it optionally when saving files.
PS. There is wrong text on image, used Photoshop JPEG setting was "11 of 12", which is much better than 80 (no matter)
That's all result of subsampling applied. https://en.wikipedia.org/wiki/Chroma_subsampling
Here is an image showing the difference between nicely-done JPEG saving lib and one using default noob way:
The typical and easiest solution is to disable chroma subsampling by setting it's block size to 1x1 pixel, so it does bare calculations and not affects image pixels.
There is big sense to do this, as it surely increases size of JPEG files slightly, but they anyway are taking much less space than PNG or any true lossless format. Thus cool quality/size coefficient is provided to store all your precious photos.
I suggest to add such fix to PB library and some kind of flag to use it optionally when saving files.
PS. There is wrong text on image, used Photoshop JPEG setting was "11 of 12", which is much better than 80 (no matter)