[QTBUG-90246] QImage::scale doesn't work for Format_Grayscale16 images - Qt Bug Tracker

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Details

Type: Bug
Status: Closed
Priority: P2: Important
Resolution: Done
Affects Version/s: 5.15.2
Fix Version/s: 5.15.9, 6.0.1, 6.1.0 Alpha
Component/s: GUI: Painting
Labels:
None

Platform/s:

Windows
Commits:
ade24763c74ce506276218ec1ce0e307301717fe (qt/qtbase/dev) 978131ba7106df99e010f5ea5559204424f29ab7 (qt/qtbase/6.0) 625a0d57aff2c0f42c832eabcc123778e0374922 (qt/tqtc-qtbase/tqtc/lts-5.15)

Description

If you try to scale a QImage::Format_Grayscale16 image the generated image is wrong. I attach a 16 bit image to test.

QImage roi;
roi.load("roiImg.png");
auto scaledRoi = roi.scaled(roi.width()/2, roi.height()/2, Qt::KeepAspectRatio);
scaledRoi.save("roiImgScaled.png");

This bug also affects QPainter::drawImage().