XnView Software

hi,
maybe this has already been discussed or i'm just not able to find the solution... however i didn't find such a topic in the forum so here is my problem:

- you have a PNG-file with a comment.
- in view mode you can edit the comment but it also changes the picture itself (not lossless?)
- in browser mode i can't even find an option to edit the comment!

so i want to be able to edit the comment without touching the picture itself (depending on the xnview 'write' options).

hopefully someone can help me. thanks.

As you already mentioned comments can only be added/edited in View mode.
However, when saving the comment to a PNG file you don't lose image data. The picture is just being recompressed (depending on the Compression level settings). This can have an impact on a file's size, but this does not hurt the quality of the image.

There's a small utility called TweakPNG that lets you insert and edit comments without recompressing the image data portion of the file.
You could add it to Open With in XnView's context menu.

See also:

• Comment problems
• PNG compression levels

hi XnTriq,

just tried TweakPNG and it works very well.

thanks for your help!

PNGs are lossless. Period.
As Xntriq said, the new PNG may be smaller than the original if your compression settings are higher than what was originally used, but PNGs never throw away info. The only way any info is ever lost in a PNG is if you choose to decrease it to 256 colors or less before saving. This color reduction is the only time data is ever thrown away with a PNG, and it only occurs that one time. From then on, you can open/save the image as many times as you want and no further data will be lost.