Page 1 of 1

Image quality issues

Posted: 2009-02-04T10:37:07-07:00
by afonit
The source file is a pdf, that looks great.

I take the pdf on linux and do 'convert -72 to jpg' and the image quality looks pretty dang bad., but if I go to os x with the pdf and open it in preview and save as a jpg at 72 dpi the image is poor but looks pretty dang good.

so the same image converted to 72 dpi, one done it imagemagick on linux/the other in preview.app on os x.

Is there a setting I am missing?



http://img18.imageshack.us/my.php?image=37500391ts9.png

Re: Image quality issues

Posted: 2009-02-04T10:51:40-07:00
by magick
Try this command:
  • convert -density 400 image.pdf -resize 25% -quality 100 image.jpg
How's that look?

Re: Image quality issues

Posted: 2009-02-04T11:15:06-07:00
by afonit
magick wrote:Try this command:
  • convert -density 400 image.pdf -resize 25% -quality 100 image.jpg
How's that look?



wow! what a difference., that is perfect, I will play with those settings, I appreciate the pointers.

Re: Image quality issues

Posted: 2009-02-04T20:40:52-07:00
by anthony
As a FYI the technique is known as Super-Sampling, and is useful for many image processing techniques.

See Text processing Postscript/PDF
http://www.imagemagick.org/Usage/text/#postscript

As well as general Super Sampling discussion
http://www.imagemagick.org/Usage/distorts/#super_sample