Re: PDFPIC issues

[Deri]

On Thursday, 22 August 2024 19:59:00 BST Peter Schaffter wrote:
> identify -version
>   Version: ImageMagick 6.9.11-60 Q16 x86_64 2021-01-25
> https://imagemagick.org
> 
> identify peachpie.pgn
>   peachpie.png PNG 150x150 150x150+0+0 8-bit sRGB 44950B 0.000u 0:00.000
> 
> groff -U -Tpdf pdfpic-test.troff > /dev/null
>   gropdf: warning: './peachpie.png' does not appear to be a pdf file
> 
> In the command line, above, the output is sent to /dev/null because
> for some reason passing groff the -z flag doesn't return the
> warning.  Seems odd.

Hi Peter,

The missing png is caused by two issues (in version 6.9):-

First, there is another perl module requirement. On debian/ubuntu it is:-

sudo apt install libimage-exiftool-perl

I will update groff_tmac.5 accordingly.

Installing this will stop the gropdf warning.

Unfortunately this does not make the png visible. This is second issue with 
version 6.9. In a pdf, transparency is handled by SMask (soft mask) which is 
an array of 8 bit numbers, one for each pixel where zero means fully 
transparent and 255 is not transparent at all. Numbers in between are 
gradations of transparency. Your png has no transparency, but has a 
transparent layer, (gimp has a menu option to delete this layer). The 
difference is that version 7 returns this layer as all 255, and version 6.9 
returns it as all zeroes. Which means that although the png is embedded you 
still can't see it because the whole image is transparent!

My investigation continues.

Cheers 

Deri