scan and compare color valus

  • Thread starter Thread starter moshebg
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moshebg

How can I compare the values off the colors between 2 scans off the
same picture/ Also I'm looking 4 programs that will give me the results
of the compare values automatically.
moshe
 
moshebg said:
How can I compare the values off the colors between 2 scans off the
same picture/ Also I'm looking 4 programs that will give me the results
of the compare values automatically.
moshe
Click to expand...

Photoshop.
Use the Eyedropper to read the RGB values.
 
i need to compare 2 different images
can i get correct answer each scanning
and can i correct one image (the same but not the wright colors)
with manipulating the amount of cmyk or i must manipulat the lab in
cmyk
moshe
 
How can I compare the values off the colors between 2 scans off the
same picture/ Also I'm looking 4 programs that will give me the results
of the compare values automatically.
moshe
Click to expand...

It depends on what you mean by compare. Do you mean statistical
analysis (like standard deviation, etc) or do you wish to analyze a
manually multiscanned image before merging or...?

In the end, all colors are just numbers. In theory, you could first
export the image as raw (in Photoshop, for example). This is to
eliminate any headers or footers, and only have a file containing
color data.

After that you could import this data into any spreadsheet, for
example, and do any kind of compare and analysis you desire. Of
course, you have to pay attention whether the image is 8-bit or
16-bit, as well as how you export the image (interleaved or contiguous
in case of a color image).

Don.
 
cmyk is for mechanical printing with separations.
Apart from that you should be in an RGB color space, AdobeRGB or sRGB.
If you are trying to center each image around the same grey point so they
have approximately the same color range the easiest way to do this is with
grey eyedrop tool in a curves or level adjustment.
If you are trying to achieve overall color management so that your first
print is a reasonable approximation of your monitor image you must learn
about the subject and calibrate your monitor.
 
moshebg said:
i need to compare 2 different images
can i get correct answer each scanning
and can i correct one image (the same but not the wright colors)
with manipulating the amount of cmyk or i must manipulat the lab in
cmyk
moshe
Click to expand...

I do not really understand, why you need to do this. If you think of
quality control patches in the printing industry, buy a
photospectrometer (GretagMacbeth, X-Rite). A scanner is a poor
spectrometer.

The easiest way to compare two images is to subtract them in a
photo-editor.
Use layers for instance in Photoshop or the composite transformation in
Picture Windows Pro. The composite transformation has a nice
registration ability.
Count the colors or stretch the contrast to see the differences.
Winfried
 
THANKS 4 ANSWERING
BUT
WHAT DO I HAVE TO BE AWER OF: CONCERNING 8 BIT OR 16 BIT?

MOSHE
Click to expand...

Byte order. In case of 16-bit data byte order can be "big endian" or
"little endian".

I'll use hexadecimal notation because it's easier to explain. Take the
following 16-bit number:
$1234

Depending on how this number is exported the two bytes representing it
may be saved in this order:
$12 $34
or, in this order:
$34 $12

You have to know this when importing such raw data into a spreadsheet.

Don.
 
Hi,
open both images in Photoshop and look at each channel (Control 1, 2, 3
for RGB) side by side. If they are real close then use the info pallete
and the color sample tool (in CS its on the same tool bar as the
eyedroper) and lay down the sample tool in the same exact place and
check.

Thanks,
Lyle P. Ecbian
 
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