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Moved RGB fix inside ImageQt class #5268

merged 1 commit into from Mar 14, 2021


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Resolves #5266. A workaround suggested in that issue is to change the user code. This PR causes the original code mentioned there to work.


Lines 203 to 205 in fdd8b68

# Fix some strange bug that causes
if im.mode == "RGB":
im = im.convert("RGBA")

This 'strange bug' is because at

QImage::Format_RGB32... is stored using a 32-bit RGB format (0xffRRGGBB).

QImage is expecting the 4th channel to be populated with 0xff (255). Calling convert("RGBA") in Pillow does this.

static void
rgb2rgba(UINT8 *out, const UINT8 *in, int xsize) {
int x;
for (x = 0; x < xsize; x++) {
*out++ = *in++;
*out++ = *in++;
*out++ = *in++;
*out++ = 255;

Without 255 values, as seen in the issue, the display in Qt is very washed out.

This PR just documents the fix slightly better, and moves it from toqpixmap() to _toqclass_helper(), so that it is also run when calling the ImageQt.ImageQt class (toqixmap() still works, since toqpixmap() calls toqimage(), which returns an instance of the ImageQt.ImageQt class).


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@hugovk hugovk merged commit 4c297ec into python-pillow:master Mar 14, 2021
@radarhere radarhere deleted the rgb branch March 14, 2021 10:16
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Qt Qt for Python, PyQt, PySide
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Successfully merging this pull request may close these issues.

ImageQt does not work as expected in PyQt5
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