PDF Question

[Jason L Blair]

Unlike other apps I'm familiar with, Acrobat doesn't seem to care much about resolution. In fact, the only mention of it I see is for output (printer) resolution. So my question is: what resolution should images be at (and what format seems to work the best) so that most people can d/l and print it so it looks crisp?

[Ron Edwards]

I second the cry for help on this matter. It's an ongoing pain in the butt.

Best,
Ron

[Jason L Blair]

I cross-posted this over at RPGNet and the basic response I got was this:

#1 - 300dpi TIFF
#2 - LZW Compression will be lost and replaced with Adobe's compression.
#3 - If you're setting PDF up for pre-press, leave all compression off.
#4 - If you choose "Downsample Image" then the image will be formatted to match your screen resolution.

None of this I knew (though I figured #1).

[Dav]

Having little in the way of "computing expertise", I am wondering why one needs to use .tif format for art.  Is .tif necessary, or would any (such as .jpeg, etc.) work just as well in terms of PDF publishing?

I ask mainly due to the fact that I will soon be making one of my first forays into PDF creation and I am just trying to get the idea.

Thanks.

Dav

[Jason L Blair]

I don't know a lot of the technical reasons being fairly new to computer-based visual design, but I think it has to do with the compression the file uses and the fact that TIFs have become pretty standard so the apps are being build around using them.

[Paul Czege]

Regarding images, the original question included a stipulation that the document would print nice and crisp. When you're concerned about print quality and you're not concerned about file size you'd never use .jpeg or .gif for images, because those two formats make trade offs of image quality for small file sizes. The .gif format trades away color depth. It's restricted to no more than 256 colors (or shades of grey). The .jpeg format provides for greater color depth, but at the expense of a reduction of image clarity. Use a paint program to zoom in on a .jpeg image and you'll see what I mean; areas of similar color adjacent to each other have been averaged together into one homogenous color. Take a look at a model's cheek or forehead or buttocks. You'll see striations of color rather than smooth transitions.

Paul

[ This Message was edited by: Paul Czege on 2001-05-08 00:32 ]

[Dav]

Paul wrote:
  "Take a look at a model's... buttocks."

Consider it done.

Seriously though, thanks for the insight.

Dav

[Ron Edwards]

Hey guys!

I found a whole bunch of websites which allow Paul's advice to be followed! Wow! Those color striations are really something.

Best,
Ron

[Jason L Blair]

Be careful though, Ron. My boss just had a fit when I was looking at the "amazing... uh... differences" between that Japanese School Girl gif and -- nevermind.

[Matt Gwinn]

I convert a lot of large files at work and we use mainly EPS images at 300dpi.  Typically we reduce the resolution down to 72 dpi for internal purposes to save on memory and load time, but when we send something to press in PDF format we keep it at 300dpi and that seems to work pretty good.

It all depends on how much memory you want to eat up.  A 200 page game will take up about 15 meg or more at 72 dpi.

As far as Tiffs go...I avoid them.

,Matt

[Clay]

JPEG images can be used without loosing detail.  While JPEG allows images to be compressed, it doesn't demand it.  When I've used JPEG I don't allow any compression (which makes it a lot like a TIFF for image resolution), and I work with a huge image.  JPEG is a native format for Acrobat documents and produces the smallest file size when you're using color images.

For black and white I worked with ecapsulated postscript at 300 dpi, as has been mentioned by others.  There's probably a better format, because I know that my Acrobat compiler spends a lot of time converting these images (unlike JPEGs), but it definitely works.  EPS black & white images created a smaller file than JPEG black and white images.

One problem that you'll run into is that JPEG files don't contain resolution information.  To get the proper resolution, figure out the desired DPI (again, roughly 300 dpi seems to work, although 150 is actually acceptable for most home printers), then multiply that by the image dimensions on the page to get the image dimension in pixels.