Bug#1123747: The built-in help doesn't mention the switch `-t` (but should probably do so). Resolution is mentioned (but should not be mentioned) when pHYs is absent.

[Emma Mueller]

Package: pngtools
Version: 0.5~git20230507.177e87f-1
$ pnginfo
Usage: pnginfo [-d] [-D] <filenames>
$ man pnginfo | grep -A1 SYNOPSIS
SYNOPSIS
pnginfo [-t] [-d] [-D] <filenames>
$ wget -q https://upload.wikimedia.org/wikipedia/commons/7/70/Example.png https://upload.wikimedia.org/wikipedia/commons/7/70/Example.png
$ grep -ai pHYs Example.png
$ diff <(pnginfo Example.png) <(pnginfo -t Example.png) | grep -i Resolution
< Resolution: 32720, 2 (unit unknown)
> Resolution: 32612, 3 (unit unknown)
As you see, the built-in help of pnginfo doesn't mention the switch `-t`, though it is implemented. Please mention this switch (or drop the support `-t` altogether if there are too many irrepairable bugs associated with it).
Further, if there is no resolution information (the pHYs chunk) in the PNG file, the resolution values output with `-t` differ from those output without `-t`. This difference is meaningless; it'd be way more consequential to drop those values completely if they are not supplied in the file.
Gratefully!
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