Datacolor User to User Support Group.

First I would like to thank mr. Tobie for the clear answer to my last question.

Another question I have is why the spyder 4 software does not allow a calibration to an 'sRGB gamma' (or does the elite version allow this?)? I understand that the gamma of sRGB is on average close to 2.2, but only on average. For lower pixel values it becomes linear and higher pixel values the gamma is closer to 2.3 (see: http://en.wikipedia.org/wiki/SRGB). Is there maybe a technical limitation in the profile parameters?

Kind regards,
Gerard

>>First I would like to thank mr. Tobie for the clear answer to my last question.

Glad it proved clear. They often seem clear to me at my end, but don't seem that way at all on the other end...

>>Another question I have is why the spyder 4 software does not allow a calibration to an 'sRGB gamma' (or does the elite version allow this?)? I understand that the gamma of sRGB is on average close to 2.2, but only on average. For lower pixel values it becomes linear and higher pixel values the gamma is closer to 2.3 (see: http://en.wikipedia.org/wiki/SRGB). Is there maybe a technical limitation in the profile parameters?

Pro only has a few basic gamma settings. Elite allows you to import or create any tone response curve you want; per channel. From your questions, it sounds like you really should upgrade. But have you actually seen the plot of sRGB's vanity curve versus gamma 2.2? If the lead in your pencil is not really sharp when you plot them both, they are simply the same line. There is no real world value of one over the other. Not anywhere close to gamma 2.3; gamma 2.21 perhaps... though the difference lowers the gamma in one area, infinitesimally, and raises it in another. 

C. David Tobie
Global Product Technology Manager
Imaging Color Solutions
Datacolor inc. 
cdtobie@...
www.datacolor.com

On Dec 10, 2012, at 4:19 PM, "gerard_culemborg" <yahoo@...> wrote:

> First I would like to thank mr. Tobie for the clear answer to my last question.
> 
> Another question I have is why the spyder 4 software does not allow a calibration to an 'sRGB gamma' (or does the elite version allow this?)? I understand that the gamma of sRGB is on average close to 2.2, but only on average. For lower pixel values it becomes linear and higher pixel values the gamma is closer to 2.3 (see: http://en.wikipedia.org/wiki/SRGB). Is there maybe a technical limitation in the profile parameters?

I did purchase the elite upgrade CD now (still the pro device, but I assume this is the same as the elite device) and have been playing with it a long time today. It seems to work fine, but there is one thing that seems to go wrong or that I do not understand.

During calibration one sets a desired color temperature (white point), say 6500K. Just as an experiment I put my monitor on 9300K through the OSD, looking very bluish. Performing an Advanced analysis - Brightness and contrast test indeed verifies that the color temperature is very high. With these settings I calibrated the monitor, assuming that the result would be a white much closer again to 6500K. However, even after calibration the color temperature is still very high similar as before. Am I misunderstanding something?

Two other smaller questions are:
- In the analysis is it possible to get the gamma with two decimals instead of one, and the color temperature not rounded to 100K?
- Is it possible to uninstall the spyder utility without uninstalling the rest of the software?

Kind regards,
Gerard

>>I did purchase the elite upgrade CD now (still the pro device, but I assume this is the same as the elite device) and have been playing with it a long time today. It seems to work fine, but there is one thing that seems to go wrong or that I do not understand.

During calibration one sets a desired color temperature (white point), say 6500K. Just as an experiment I put my monitor on 9300K through the OSD, looking very bluish. Performing an Advanced analysis - Brightness and contrast test indeed verifies that the color temperature is very high. With these settings I calibrated the monitor, assuming that the result would be a white much closer again to 6500K. However, even after calibration the color temperature is still very high similar as before. Am I misunderstanding something?

It is a bad idea to set the hardware controls to an extreme setting, just to see if the video corrections can play Superman and fix it. If you are targeting a whitepoint (not native whitepoint, which will leave it where it is) and a defined luminance (not native luminance) that is close to the max possible luminance, then you are asking for two mutually impossible things at once. There are other possible reasons your results would not be as expected, but I try to limit myself to dealing with questions about appropriate uses of the products, not intentional abuses. 

>>Two other smaller questions are:
- In the analysis is it possible to get the gamma with two decimals instead of one, and the color temperature not rounded to 100K?

Gamma is a single number curve construct: all points along the curve need to fit a specific shape to match that number. As in any case where a single number represents an array of values, the answer is extremely simplistic. Adding more units to such a simplification would only encourage people to believe those extra digits were meaningful. If they are not significant, they should not be shown. 

The same applies to"K" values. 100K already represents an actual measurement variation in the range of 0.0x; going to 0.00x would let people assume that such tolerances are meaningful.

If two displays with a gamma difference in the range you suggest, and a K difference in the range you suggest we're set up in separate viewing areas, and you compared the same image on one of then, then moved to the other viewing area, and viewed it on the other, it would be impossible to distinguish any difference between the two. That is real world tolerances.

>>- Is it possible to uninstall the spyder utility without uninstalling the rest of the software?

It is possible to turn it off; doing so on a Windows machine is guaranteed to eliminate your color management. On a Mac, it will cripple it, but may not totally invalidate it. In either case, we are talking about things you should not do, as we were in the first section above. 

What you suggest falls into the "PC tuning" category. People who want to eliminate all background processes that might use a few cycles. The question here is what is more important to you: accurate color, or stripping down your system to "run lean"?

C. D. Tobie
Global Product Technology Mngr.
Imaging Color Solutions
Datacolor.com
CDTobie@...

On Dec 21, 2012, at 4:59 PM, "gerard_culemborg" <yahoo@...> wrote:

> I did purchase the elite upgrade CD now (still the pro device, but I assume this is the same as the elite device) and have been playing with it a long time today. It seems to work fine, but there is one thing that seems to go wrong or that I do not understand.
> 
> During calibration one sets a desired color temperature (white point), say 6500K. Just as an experiment I put my monitor on 9300K through the OSD, looking very bluish. Performing an Advanced analysis - Brightness and contrast test indeed verifies that the color temperature is very high. With these settings I calibrated the monitor, assuming that the result would be a white much closer again to 6500K. However, even after calibration the color temperature is still very high similar as before. Am I misunderstanding something?
> 
> Two other smaller questions are:
> - In the analysis is it possible to get the gamma with two decimals instead of one, and the color temperature not rounded to 100K?
> - Is it possible to uninstall the spyder utility without uninstalling the rest of the software?

Thanks again for the answers.

I did not actually try to do a calibration to 6500K based on a 9300K hardware setting. I just did this to verify that the color temperature did not really changed in my system (soemthing that should be obvious with this large separation in color temperature). The reason why I did this was that when I put the hardware on 6500K and tried to calibrate to 6500K, it consistently stayed at 6900k or 7000K in the advanced analysis done right after the calibration, so I was wondering if the calibration was not done right or something else was going on.

I thought you pointed me in the right direction with the 'not native' settings, because I did indeed have the luminance in the native setting for the calibration before. So I changed it to 120 cd/m2 and adjusted the brightness as indicated in the calibration procedure. Unfortunately, in the advanced analysis it still gives a value of 6900K or 7000K as if nothing has changed for the white point. The weird thing is that during calibration the values shown indicated that it iterated to (0.314,0.330) which indeed is close to 6500K, but the measurement of the advanced analysis says (0.305,0.328) which is indeed 6950K. Weird may also be that the brightness differed from 120 cd/m2 in the calibration to 132.7 cd/m2 in the advanced analysis (measured directly after the calibration, with the spyder hanging nearly in the same spot both times). Also the Spyderutility has not been touched all this time. I am using windows 7 (64 bits) and spyder4elite software version 4.5.4 with a Spyder Pro device (but I assume that the spyder pro and spyder elite devices are the same?). Does all this ring a bell for what is going wrong? Is there a bug in the calibration, a bug in the advanced analysis measurements, is the calibration in the windows color management not correct, am I doing something wrong or misunderstanding something? 

Kind regards,
Gerard 

-----------------------

> During calibration one sets a desired color temperature (white point), say 6500K. Just as an experiment I put my monitor on 9300K through the OSD, looking very bluish. Performing an Advanced analysis - Brightness and contrast test indeed verifies that the color temperature is very high. With these settings I calibrated the monitor, assuming that the result would be a white much closer again to 6500K. However, even after calibration the color temperature is still very high similar as before. Am I misunderstanding something?
> 
> It is a bad idea to set the hardware controls to an extreme setting, just to see if the video corrections can play Superman and fix it. If you are targeting a whitepoint (not native whitepoint, which will leave it where it is) and a defined luminance (not native luminance) that is close to the max possible luminance, then you are asking for two mutually impossible things at once. There are other possible reasons your results would not be as expected, but I try to limit myself to dealing with questions about appropriate uses of the products, not intentional abuses.