This is a patch over MR !108 by @sandsmark. Martin has done a great job implementing support and I find it a shame not to use it.
I made sure that the results are the same as the current version and fixed the problems of pixels with wrong colors with color depth grater than 8 bits. I also fixed conversion errors on mask and gray images (16/32 bits).
Unfortunately the internal rendering engine of the original code is 8-bit so I always forced the output of 8-bit images to correct the problems (see image below). Since it is a plugin with a "rendering engine", the tests to seriously validate it are potentially endless (as the original version is not perfect).
Errors of the original version of the MR (right) which should no longer occur:
- fix buffer overflow with corrupted images without image data
- fix unable to read very small images (e.g. 1x1 px)
- new test cases added
- detect incomplete files by checking the end of streams as written in the specs
- Standardized the quality parameter between 0-100
- The value -1 is the default value of Qt plugins and is managed
- Negative values other than -1 are used as flags to activate the custom mode
- 1-bit writer: checks where is black and use NOT operator only if needed
- Fix images with witdh == 65536(*)
- Checks result of disk writes and reads on all formats
(*) PCX formats support images with with of 65536 but only if the header field bytesPerLine is valid (no overflow). This means that the width 65536 is supported on 1bpp images only.
The previous version of the plugins wrote an image with width of 65536px in the wrong way and it was unable to read it (wrong image returned). I verified that Photoshop and Gimp weren't able to read the image either.
- Fix wrong RGB channel order if image format is other than (A)RGB32
- Write right resolution
- Set right resolution on image load
- Return false on write error
- Save images with depth greater than 24-bits
PSD files are saved with as alpha premultiplied. The problem is that alpha refers to white instead of black so it requires transformation formulas. Then, to conver PS premultiplied to QImage premultiplied you have to use the following formula:
* V = Alpha + Vps - Max (C, M, Y, K, R, G, B, Gray, L\* components)
* V = Vps + (Alpha - Max + 1) / 2 (a\*, b\* components)
Where Max is the maximum value depending on the image depth and Vps is the valued read from the file.
- If the size of an item is greater than 1 byte, it must be ensured that it is not partially read.
- In many readings, LibRAW gives an error if a partial number of items are read so I always try to read everything.
- Fix parasite "gimp-comment" not set due to null QImage
- Support to parasite "icc-profile" using Qt 5.14+ API
- Added parasite "gimp-image-metadata" as QImage metadata "XML:org.gimp.xml"
- Added a XCF with XML metadata and icc prifile embedded in autotest folder (generated by GIMP 2.10.30)
- Tested with Qt 5.15.2 and Qt 6.2.3 under Windows and Qt 6.2.3 under macOS
