15 Aug
2006
15 Aug
'06
9:43 a.m.
Barry Watzman wrote:
Yes, it's lossy compression, but if you use a high-quality setting (which
was my point of 5K to 10K file size per square inch for color, or about 1/3
that for monochrome), you will never notice ANY difference. The size of the
document is irrelevant, since as I said, "5K to 10K ***PER SQUARE INCH***".
The size of the *original* document is important as it has been
scaled down to print on a page 1/4 it's original size. I.e.
you start to approach the resolution of the marking engine
(e.g., 1 pixel wide lines) which, mathematically, looks like
a very high frequency component.
RE:
[fixed indents]
But doesn't JPEG use lossy compression?
Yes. You can adjust the "quality factor" but I think this
would be A Bad Choice. Especially given my original comment
that the documents are D-size reduced to B-size before printing
(i.e., the text/lines are VERY fine and apt to disappear
in the DCT application within the JPEG encoder.)" Larger documents produce larger files, but the quality
loss for larger
documents is no greater than for smaller documents ... which is to say,
imperceptible. TRY IT, and compare the results. I suggest that you will
not notice ANY difference between JPEG and TIFF, no matter what you do, no
matter how you examine them. I have scanned nearly 40,000 pages now, plus
almost 10,000 color photographs, since 2001. There is no good reason to use
TIFF instead of JPEG, as long as you don't try to achieve excessive
compression levels with JPEG (and at 5K to 10K per square inch for color,
you won't be doing that -- that equates to 500K to 1 megabyte for an 8.5" x
11" color page). In fact, I often find that I can go down to less than 100k
bytes per page (that's down towards and below 1K per square inch), but this
is too much compression for some documents.
I'll play with it "as an exercise". I suspect I will find
fuzzy signal lines (i.e. as if they were anti-aliased) :-(
Let me dig up some suitable drawings (any B-sized photocopies
will have too much "toner spread" to test the fine line issue)