Opened 5 years ago

Closed 3 years ago

Last modified 3 years ago

#3650 closed Bug (Fixed)

Image size off-by-one error with_GDIPlus_ImageResize

Reported by: anonymous Owned by: Jpm
Milestone: Component: Standard UDFs
Version: Severity: None
Keywords: Cc:


The function _GDIPlus_ImageResize creates images that seem to have an off-by-one error regarding the size of the source image placement inside the destination bitmap.

Please see the attached images. The code below was used to up-scale TestImage.png to TestResult.png, and then TestResult.png was viewed in Paint.Net. In the screenshot for Paint.Net you can clearly see the resulting image has a transparent border showing through along the right and bottom edges, while the left and top edges appear as they should. While the resulting image is the correct number of pixels overall, the content inside is slightly small, although not obvious since the missing part is transparent.

This seems to suggest the source image was placed into the destination image with the bottom right coordinates specified one x pixel and one y pixel less than ideal.

Test Code:

#include <GDIPlus.au3>
Local $hImage = _GDIPlus_ImageLoadFromFile(@ScriptDir & "\TestImage.png")
Local $iWidth = _GDIPlus_ImageGetWidth($hImage)
Local $iHeight = _GDIPlus_ImageGetHeight($hImage)
Local $hBitmap = _GDIPlus_ImageResize( _

$hImage, $iWidth * 4, $iHeight * 4, _

_GDIPlus_ImageSaveToFile($hBitmap, @ScriptDir & "\TestResult.png")

See also (somewhat) related ticket # 3647

Attachments (3)

TestImage.png (2.5 KB) - added by anonymous 5 years ago.
TestResult.png (53.4 KB) - added by anonymous 5 years ago.
PaintScreenshot.png (103.6 KB) - added by anonymous 5 years ago.

Download all attachments as: .zip

Change History (9)

Changed 5 years ago by anonymous

Changed 5 years ago by anonymous

Changed 5 years ago by anonymous

comment:1 Changed 5 years ago by anonymous

I made a fix which corrects this issue as well as the issue on ticket #3647. The fix is uploaded to ticket #3647.

comment:2 Changed 4 years ago by anonymous

Further testing reveals that it's not the bottom and right edges that are missing, but rather the entire image is shifted up and left by one pixel, so it's the top and left edge of the whole image is being clipped.

comment:4 Changed 3 years ago by Jpm

  • Owner set to Jpm
  • Status changed from new to assigned

comment:5 Changed 3 years ago by Jpm

  • Resolution set to Fixed
  • Status changed from assigned to closed

comment:6 Changed 3 years ago by Jpm

fixed by #3647

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