serious noise problems in JPEG exports

[Jason Winshell]

JPEG - serious noise problems in JPEG exports

Omnigraffle 2.1.1 beta 1 (v34.19)
OS X 10.2.3

Create a simple document with consisting of a rectangle with a 1 pixel
black border and a white fill, no shadows.  In the middle of that rectangle
create a smaller solid black rectangle, no shadows.

***************
*             *
*    *****    *
*    *****    *
*    *****    *
*    *****    *
*             *
***************

Export this Omnigraffle document using the best JPEG setting
(biggest file, least lossy).

Open the the resulting jpeg file with PhotoShop.  You will find
large number of faint grey pixels near the black area.  Using
the "levels" tool you will see all the gray pixels.  These are
not pixels are not anti-aliasing.  The pixels are noise.

Repeat the experiment by creating the same graphic in Photoshop.
Save the jpg at the highest quality level.  Reopen the jpg
file produced by Photoshop.  You will see it has no noise -- just
a nice looking black and white image.

Same is result if you use GraphicConverter (using Quicktime library
for jpeg i/o).

Bottom line: Omnigraffle is not performing JPEG i/o properly -- noise
always results in inappropriate ways.  Omnigraffle cannot produce
nice looking JPEGs for plain black and white diagrams.

Arggh!
-- 
-------------------------------------------------------------------------
Jason Winshell, Principal Consulting Engineer     jwinshell at bearriver.com
Bear River Associates, Inc.                      http://www.bearriver.com