03-05-2021, 05:48 PM
You want to ensure that any trace of the original background is removed? What is the final exported image format that worries you ?
My tuppence worth
For Jpegs there might be a residual thumbnail in the exif data that shows the original background. It will be small (my camera = 160x120 pix) but viewable.
You can extract the thumbnail with exiftool . Zero file size = no thumbnail.
To get rid of all exif data get the little command line utility jpegoptim It is in the 'buntu repo. Of course you can just untick all the options in the Gimp export dialogues but thumbnails can carry over.
For png's with transparency there is the "saved colorpixels from transparent pixels" option. Turn that off when exporting your png. You can easily check. Open the png in Gimp, use the eraser tool with anti-erase (bottom of the tool options) checked. Does the erase uncover the transparency ? What is shown BG color or original ?
Tif's might be another format that can retain a thumbnail. Gif uses a colormap, not a problem.
My tuppence worth
For Jpegs there might be a residual thumbnail in the exif data that shows the original background. It will be small (my camera = 160x120 pix) but viewable.
You can extract the thumbnail with exiftool . Zero file size = no thumbnail.
Code:
exiftool -b -ThumbnailImage image.jpg > thumb.jpgFor png's with transparency there is the "saved colorpixels from transparent pixels" option. Turn that off when exporting your png. You can easily check. Open the png in Gimp, use the eraser tool with anti-erase (bottom of the tool options) checked. Does the erase uncover the transparency ? What is shown BG color or original ?
Tif's might be another format that can retain a thumbnail. Gif uses a colormap, not a problem.