Stroke around PNG with transparency in TCPDF
When you output a PNG image with transparency via TCPDF, a gray border appears at the junction of the transparency.
The original image has no borders
How can this be overcome?
2 answers
Maybe some configuration.
Most likely, this is due to the fact that when you change the size, the borders begin to be drawn.
Knowledgeable people recommend adding an 8-bit mask. example of an alpha channel
I haven't tried it myself, but the example from the official website should help.
We also encountered a similar problem when printing documentation. We couldn't find a good solution, so instead of transparency, we just make a white background for all the images in the image editor.
With a white background, there is no problem with the outline, but it is a crutch. At that time, the decision was made and did not change further.
The day before, I was again puzzled by drawing PDF documents, I began to look at what was happening with this topic - I found this post.
Look to the side https://github.com/tecnickcom/TCPDF/blob/master/CHANGELOG.TXT
The new version is still in development, but according to Changelog: 6.2.11 (2015-08-02) - Bug #1070 "PNG regression in 6.2.9 (they appear as their alpha channel)" was fixed.
Try creating a document with a new version of the library, from GitHub. I tried it - there are no frames (or I don't see them).