PNG with transparency is black when resized without ratio locking

Issue created

LAMBLIN created this issue on 07/Aug/25 14:53

Summary:	PNG with transparency is black when resized without ratio locking
Issue Type:	Bug
Affects Versions:	16.10.9, 17.4.3
Assignee:	Unassigned
Attachments:	ibm-spectrum-scale.png, image-2025-08-07-14-46-13-265.png, image-2025-08-07-14-49-07-512.png
Components:	Image
Created:	07/Aug/25 14:53
Labels:	regression
Priority:	Minor
Reporter:	LAMBLIN
Description:	Steps to reproduce: include a PNG image with transparent background in a page with the following parameters - unlocked ratio, works also with only height set: Image provided for example purpose: Expected result: The image is correctly displayed Actual result: The image is displayed with a black background - in fact the image seems displayed in inverted black and white. Seems to be a regression of https://jira.xwiki.org/browse/XWIKI-15062

Changes by LAMBLIN on 07/Aug/25 14:54

Description:	Steps to reproduce: include a PNG image with transparent background in a page with the following parameters - unlocked ratio, works also with only height set: !image-2025-08-07-14-46-13-265.png! Image provided for example purpose: !ibm-spectrum-scale -1 .png \|thumbnail ! Expected result: The image is correctly displayed Actual result: The image is displayed with a black background - in fact the image seems displayed in inverted black and white. !image-2025-08-07-14-49-07-512.png! Seems to be a regression of https://jira.xwiki.org/browse/XWIKI-15062
Attachment:	ibm-spectrum-scale.png
Attachment:	ibm-spectrum-scale-1.png

Changes by Simon Urli on 12/Aug/25 10:55

Priority:

Minor Blocker

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