# Re: Probable Bugs & Suggestions

Matto Marjanovic (maddog@mir.com)
Thu, 18 Dec 1997 22:05:34 -0500

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o the scan resolution is not saved correctly, i.e. when setting it to 200
dpi it is set to 198 after a new start of xscanimage

[with regards to the Microtek E6...]
Yes and no. The resolution can only be set in 1% increments (e.g. 6dpi for
the E6) -- 198 is valid, 200 is not. The scale on xscanimage doesn't
reflect the quantization right away (fixable?).
[Actually, there are special resolution codes for 200dpi and 400dpi; that's
on low-end of the ToDo list.]

o setting the value for Exposure to -13 or less results in an error
(besides 0 is 0 when coming from positive values and -0 when coming
from negative ones)

I don't get any errors, but I do get a really ugly buzzing noise with values
< -13. Beats me. I can see the -0 thing (happens when you slide the slider
with the mouse) --- that would be another GTK/xscanimage thing.

o trying to change any parameter during a preview or a scan results in both
xscanimage and the scanner to go nuts. There is a error popup and the
following error message is repeated eternally on the terminal where
xscanimage was started:

Error: Failed to set value of option brightness: Device busy.

I don't know about *all* parameters, but I do see this behavior with sliders;
looks like xscanimage drops into a loop of sorts when it doesn't get what it
wants.

While a scan is in progress, the microtek backend responds to any requests
to change parameters with SANE_STATUS_DEVICE_BUSY... Is this a reasonable
behavior? This response is actually not enumerated as a valid response
to sane_control_option in the API documentation. Should the frontend retry
on its own volition, or pop up an error for the user and drop the issue?

o when using xscanimage as a gimp plugin the transfer of the image from
xscanimage to gimp sometimes doesn't seem to work. In fact, nothing
seems to happen and monitoring the process list with top reveals that
xscanimage is growing and growing and xscanimage and gimp use nearly
the whole CPU. (When xscanimage reached 23 MB I killed it, and that
was for a fairly small image of about 5 MB.)

???????? Never had any problem like this.

o Automatic Color Calibration: Ok, although I know nearly nothing about
scanning and image processing, here is my thoughts about color calibration
for a certain printer. Suppose you have an image with three linear gradient

perspective, is that it's crazy stuff. A lot of standardization structure
is already in place; anyone who wants to try this should spend some time in
the library first, and realize that what you really want to do is to
calibrate your scanner, printer, and monitor independently to CIE standard
color indices.

-matt m.

ps: As always, the general rule is if you have a reproducible problem, send
an error log... helps immensely with tracking down what is going on inside.
(For example, I know of at least three different model codes for the
"Scanmaker E6" --- who knows which one anyone has, and what the subtle
differences in behavior might be?)

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