#556 Horizontal lines artefacts when converting eps to jpg

[ioio]

Dear team, first, thank you for GraphicsMagick !

I would like to report an issue with eps to jpg (and probably other raster formats) conversion. when a concave path is converted, horizontal lines appear in the result image, please see attachments for an reprocase eps and result jpg.
the following parameters were used :
gm convert -density 100 -geometry 50% -quality 100 -strip file.eps file.jpg
i usualy use much higher density, and the issue still occur and can be seen when zoom in.

thanks for your support

[Bob Friesenhahn]

On Mon, 2 Apr 2018, ioio wrote:

I would like to report an issue with eps to jpg (and probably other raster formats) conversion. when a concave path is converted, horizontal lines appear in the result image, please see attachments for an reprocase eps and result jpg.
the following parameters were used :
gm convert -density 100 -geometry 50% -quality 100 -strip file.eps file.jpg
i usualy use much higher density, and the issue still occur and can be seen when zoom in.

This does not happen for me. Ghostscript is used to render the EPS to
a raster image and libjpeg is used to compress it.

What versions of Ghostscript and libjpeg are you using? Please
specify the variant of libjpeg (IJG or Turbo, or some other one).

If you remove the '-geometry 50%' argument, does the problem go away
in the output image, or is it still there?

Bob

[ioio]

Hi Bob, thanks for your answer. i was not sure if this comes from Ghostscript or GraphicsMagick, thanks for clearing the process.
i thought i use latest version of Ghostscript, i'll have to check that . i don't remember installing any specific libjpeg so i must use what was bundled with GraphicsMagick . but i am pretty sure this is not a jpeg compression issue since it is really related to each concave points in the rendered path si it must come from Ghostscript.
if i remember correctly, the -geometry 50% had no influence on the result, i used it to reduce the aliasing.

thanks !

[ioio]

Hi again, seems Ghostscript released a version 9.23 on march 21, and it fixed the problem ! thank you for pointing in the right direction and sorry for that "false" issue !

[Bob Friesenhahn]

Was a Ghostscript bug.