Why is text in Acrobat files so hard to read?

Is it just me or is text in Acrobat files hard to read? Somehow the edges of the text seem much blurrier than any of my computer’s fonts. This is viewing at 100%, with text smoothing on (looks much worse without it). Even zoomed to 400%, the edges don’t have that “crispness” that I associate with other things on my monitor. I played around with the CoolType settings, but nothing seems to make things better, just worse.

Is this just a tradeoff of the pdf format? Am I the only one having trouble here?

I have a nice CRT (19" Sony G420) and decent videocard running at 85hz/1024x768, for what it’s worth.

They print nice, tho.

capn

One of a PDFs best features is that it uses vector fonts, so that they are crisp and sharp edged no matter what the resolution or zoom.

So you must have some setting wrong, or aren’t using vector based fonts.

Capnfutile, what type of file was this before conversion to PDF?

It depends on the resolution of the original file, before it was saved as a pdf. Are you refering to the pdfs you have made, or the ones you’ve received from other people? If **everyone’s **pdfs look like crap to you, you’ve got a problem.

Beats me, but it was one that came with a Photoshop upgrade (new features, etc). I figure Adobe knows what they’re doing!

capn

Unless you are working with an image of text, this should not be possible.

The Portable Document Format (PDF) is a way to save a document such that you preserve all aspects of page layout, including the use of special characters and even (monochrome) drawings. This involves using a programming language that encodes not dots, but shapes. That is, you don’t preserve the position of every pixel on the screen, you note down the lines and shapes used to put those pixels on the screen. This way, you can scale the image as much as you want and never lose resolution.

PDFs can also contain images, which (unfortunately) do preserve the location of every pixel. That means they only look good at one size, and you need lots of software and some hard work to scale them nicely.

Now that I’ve told you why it shouldn’t happen, you’ll need to find someone to tell you why it is happening. Unfortunately, I’m probably not that guy.

(Why all the talk of vectors? Because mathematically, what the PDFs contain can be represented as vectors, and you can use math to make those vectors do whatever you want.)

Doing research I’ve opened hundreds of pdf’s on the net. Some, indeed many, of them appear on screen so blurry as to be unreadable. They have to be printed so that they can be read.

In my experience, and despite all of the minor frustrations of the software I use, PDFs are generally quite readable online.

I’m using Gnome Ghostview on Fedora Core 1, but this shouldn’t matter, in theory.

What you are probably running into is a PDF file created with bitmapped fonts instead of vector fonts. PDF does handle vector fonts (as others have mentioned), which scale very well and therefore display well on your screen. But, that doesn’t guarantee that every PDF file is made using those fonts. In particular, many people create files with Postscript Type 3 fonts (which are bitmaps), which is the default on some document preparation systems. These font’s print perfectly well, but show up “fuzzy” on the screen. Type 1 fonts could be used instead (which are vectors), and these will display cleanly on the screen, but most people don’t know to make that change in their software.

So, I think the bottom line is that it is not your system, but rather it is the fault of whoever made it. There is nothing I know of you can do after the fact to fix it. It should print very well, in any case.

Was this a technical or scientific paper by any chance? This problem is notorious with a typesetting system called LaTeX, popular with people that have to set equations and such. The default settings for one component of this process (dvips, for people that are familar with it) often uses Type 3 fonts by default. This can be changed, but most people don’t take the initiative. The references I know about the problem are mostly in terms of this typesetting system, but the problem descriptions should tell you a little about what’s going on.

Some links:

First result searching “type 3 font” on adobe.com

One description for LaTeX users

Another discussion for LaTeX users, with some interesting links

Also, a lot of PDFs are archived paper documents, scanned as big raster files (TIFF, JPEG, etc.). When creating a PDF, you have the option of compressing the content. The text compression algorithms are lossless, but you can choose lossy JPEG compression for graphics.

This can lead to files made this way being blurry on screen. Try using the text selection tool in Acrobat Reader. If you can’t select the text, it’s actually a graphic.

If your text in PDF files is hard to read, it’s probably because they are bitmapped, most likely a scanned image.

Try resetting your zoom level to an even multiple of 2 or 1/2 : 25%, 50%, 100%, 200%, etc. The resampling of the text will look much better. Even 150% (three halfs) will appear much better than some odd fraction like 123% or 79%.

Crozell’s explanation sounds good to me. Lots of the papers were technical and contained equations, now that I think of it. (Many were legal files of court cases, though.) And as I mentioned, they printed out perfectly. Only the screen image was blurry.