File size, compression and quality?
btrc:
I'm working on an interactive character sheet for a project, and the sheet itself is going to be a full-page jpeg background image in a pdf. The image is color, has graphics and text. My query is for anyone who has tried to optimize such for home printing.
For any given final file size (say 1.5 megs) and a resolution of anywhere between 300 and 600 dpi, what do you think is the best compromise for print (not screen) quality? A 600dpi image with a lot of compression, a 300dpi image with much less compression, or some level in between? 600dpi gives me best quality text, but loads of compression artifacts on the image, while 300dpi gives me less sharp text (especially against a variable color background), but much less in the way of compression artifacts.
Obviously, I'm going to be trying out a lot of variations, but I just wanted to see if anyone else has ever had to work with this sort of problem.
Greg Porter
BTRC games
jerry:
Quote from: btrc on January 21, 2008, 11:15:41 AM
I'm working on an interactive character sheet for a project, and the sheet itself is going to be a full-page jpeg background image in a pdf. The image is color, has graphics and text. My query is for anyone who has tried to optimize such for home printing.
It's a pain. Is there a reason that the text has to be part of the jpeg? If you can move the text out of the JPEG and into the PDF (that is, use text instead of images to display the text) that will make optimizing the JPEG much easier.
JPEG is designed for photographs (or photograph-style images). It does poorly on images with few colors and sharp lines, such as text.
If I absolutely have to pre-render text into an image, I'll try hard to use PNG instead of JPG--which means using cartoon-style imagery (that is, few colors and sharp edges) if I need to keep file sizes down.
So short answer, it would probably help to see an example of the imagery you're trying to use.
Jerry
btrc:
Jerry, the image in question is the last page at:
www.btrc.net/pub/vq04.pdf
As a character sheet, most of the program/user-entered info will be text in Acrobat, and will print just fine using the embedded fonts. However, the character sheet has text of its own, some of which uses photoshop effects that Acrobat can't duplicate. I believe the background image in the current file is a 600dpi high compression jpeg.
Also, for importing page backgrounds like this, the file format has to be pdf, though I can generate that pdf from just about anything and apply jpeg compression to it for the final result.
Greg
BTRC
Paul Czege:
Hey Greg,
That's a gorgeous sheet.
I've never done this...but why not achieve your text effects in Photoshop, and then export the text separately from the background as 600 dpi png image with transparency, placing it over the background in your pdf, which you've saved as a 300 dpi png (to achieve fewer compression artifacts)?
Paul
jerry:
What Paul said: if it has to be images, use software that supports layers, and export the layers to the appropriate format; PNG for things that can't compress without losing quality, and JPEG for things that can. (If it has to have an alpha channel, which it will if it isn't the bottom layer, it will need to be PNG also.)
Judging from what you've done, the software you're using already supports layers, so all you have to do is move things into separate layers. But if not, Photoshop and Illustrator both support layers, as do the free GIMP and Inkscape. (Just remember that GIMP doesn't support CMYK, if that's a deal-breaker for you.)
Jerry
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