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Duncan Paton Dec 11, 2002 2:51 PM

Adobe Colourspace query
 
As I use photoshop 7 I have selected the Adobe colourspace on my 7Hi. When I view pictures in Photoshop I cannot see any difference, however when I print them on my Epson 890 the colours appear to have changed, giving a more reddish warmer look to the picture. It is not really a cast as some white areas still appear white (not pink). Neutral colurs with a green tint appear to have been changed to browns.
I am not sure if the problem is with my printer as it reproduced colours from my Fuji MX1700 perfectly. I tried doing a print from my old camers after printing the problem 7Hi image and this too came out with enhanced red. I then ran out of paper, so I have not been able to conduct further experiments.
I have read that I need a plugin to use the adobe colourspace, however the image appears ok in photoshop.
Can anybody explain what the advantages of the adobe colourspace :?: are - if any and how to print with it.

Thanks

Duncan

NHL Dec 11, 2002 6:45 PM

FYI

AdobeRGB is proprietary to Adobe, whereas as your PC screen (not MAC) is calibrated differently to an sRGB standard proposed by HP and MSFT:

http://www.w3.org/Graphics/Color/sRGB.html

The AdobeRGB has a wider mask than sRGB. Printers again have a different colorspace altogether...

Duncan Paton Dec 11, 2002 7:55 PM

Thanks for the speedy reply. I think that it will take a few days to digest the article.
The adobe colourspace is presented as a feature, however if I cannot see the difference on screen and it is causing problems with the printer, what is the point of having it?

Thanks


Duncan

NHL Dec 11, 2002 8:23 PM

If you look at an AdobeRGB picture with an sRGB monitor you should see a difference right away. Take for example theses representations (the only one I can remember at this time that shows an AdobeRGB space):

http://www.dpreview.com/reviews/mino...ge7/page13.asp

The color area inside the black triangle is bigger for AdobeRGB than sRGB, therefore a picture captured in AdobeRGB will be compressed down when viewed inside the sRGB black triangle -> the color area will be smaller hence a flatter colored picture. However; when you import the AdobeRGB image inside Photoshop there's actually more datapoints from the file for Photoshop to work with, but Photoshop in turn displays (ie maps) it's picture to an sRGB for the PC hence you don't see a difference like before.

In reality the AdobeRGB triangle is not only just larger, but the center point (ie white area) is not exactly at the same center as in sRGB hence the color shift in your observation when the colorspace get shrunken down by squeezing AdobeRGB colorspace onto sRGB... without remapping.

A printer again has a different triangle mask, with again a different offset, and that's why icc profiling is so important. It allows the mapping from one device to another ie camera -> PC screen -> printer. The problem is most people already started with an uncalibrated monitor so the profiling is pretty much useless! BTW the Spyder from ColorVision is on sale @ the dpReview site and is a good beginning if you want to get started!

If you are unfamiliar with this whole process, stick with sRGB for the moment. You are just working from a smaller area that all. The tradeoff is that you might not extract the optimum result especially if the printer you use is mapped to a different space that is slighly larger than your PC monitor. Remember a MAC monitor has a totally different colorspace than a PC as well...

DigiCamMan2 Dec 11, 2002 9:20 PM

Epson has downlodable plugins for Adobe Photoshop that ensure the colors printed closley match those captured. You may want to try using rthe plugin for your printer model with Adobe and see if this corrects your color issues.

NHL Dec 13, 2002 12:55 PM

Just came across this today, hope it helps:

Quote:

In general terms, Adobe RGB has a larger gamut than sRGB, and allows you to work in more saturated color (not more colors) than sRGB. Adobe RGB more closely matches the color gamut of photo quality color printers. It is a good choice for those users working in RGB with output going to print, either as RGB files for photo quality inkjet printers, or, after conversion, as CMYK files for offset printers. sRGB, with its smaller color gamut, is intended to match the characteristics of the average PC monitor. It is a good choice for images going to the web and for images going to color printers with limited color capabilities.
http://www.promarketinc.com/technica...paces_pt2.html

Quote:

sRGB reflects the characteristics of the average PC monitor. If you are producing graphics to be viewed on the Web, sRGB will reflect what most viewers see. The downside to sRGB is that it has a limited color gamut and cannot represent as many colors as other color spaces. It is not a good choice for professional prepress users since too much of the CMYK gamut lies outside of it.
http://www.adobe.com/support/techgui...op/rgbset.html

Duncan Paton Dec 15, 2002 4:47 PM

Thanks again for the replies. I bought some more paper and did a print with the epson custom settings set to sRGB however the colours are still wrong.
I bought the correct epson ink cheaply at a computer fair and I am beginning to wonder if this is where the problem lies.
I am sorry that I have not had time to read all of the links but I have had to study for a job interview. When this is over I will catch up with the reading and conduct some 'scientific' experiments and report the results.

Thanks again

Duncan

NHL Dec 15, 2002 6:33 PM

With the Epson printers you can store the profile of each ink type under the custom setting. I name mines with the name of the compatible cartridges after adjusting the different color sliders. This way you can go back and forth between different vendors... yea a common problen when everyone try to save money on consumable!

zhu001 Dec 17, 2002 3:17 PM

i have read the website:

http://www.dpreview.com/reviews/mino...ge7/page13.asp


i think this refers to old frimware of diamge 7 only.

i always opened photos directly (dimage 7i) until i read the that website feature 13. i didnt see any changes of color wheather thru dimage viewer or directly open from the file.

did i miss something here?

NHL Dec 17, 2002 5:19 PM

Quote:

I always opened photos directly (dimage 7i) until i read the that website feature 13. i didnt see any changes of color wheather thru dimage viewer or directly open from the file.
No you did not miss anything on the 7i (sRGB only)... On the original D7 (proprietary), and the D7Hi, where the output can be mapped to AdobeRGB, theses colorspaces are larger than the sRGB only of the 7i (ie the 7Hi output will be the same as the 7i if set on Natural sRGB).


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