Re: poor quality of on screen pdf

Subject: Re: poor quality of on screen pdf
From: "Dick Margulis " <margulis -at- mail -dot- fiam -dot- net>
To: "TECHWR-L" <techwr-l -at- lists -dot- raycomm -dot- com>
Date: Fri, 31 May 2002 11:09:57 -0400


Jennifer,

Here is one possible reason. This may not apply in your case (I can't tell from the information you've provided).

The rendering of PostScript (PS) is different from the rendering of Encapsulated PostScript (EPS).

When PS is rendered, the theoretical percent of a given pixel that is covered by a shape is calculated and that pixel is assigned a color that is the calculated percentage of the specified color. Here is an example: If you have black type on a page and the left stroke of a capital A theoretically covers 50% of a particular pixel, that pixel is rendered in a 50% tint of black.

When EPS is rendered, if a shape touches any part of a pixel (even just grazing the corner), the entire pixel is rendered in the color of the shape.

This difference is in the published standards for PS and EPS; it is not a mistake (no matter how bad it looks on screen).

So, when your publishing program or graphics program creates the output stream that Distiller is going to render, if the output is EPS, it's going to look jaggy on screen. This applies particularly to fonts that have been converted to outlines (something we do commonly in Adobe Illustrator, for example); but it affects other shapes, too.

Could that be the source of your difficulty?

Dick

Jennifer Maitland <jlm -at- kwi -dot- com> wrote:

>Can anyone tell me why the PDFs I create look fine when printed out, but
>terrible on screen? I don't really have any images in them, but the fonts
>are fuzzy and the flow charts have some thick lines and graininess.....


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