Datacolor User to User Support Group.

>Colorvisionstartup.exe is ColorVision's application which loads the
calibration profile into the video card. What I am unsure is if I
really need it.

You say .exe, so I will have to assume Windows. And you say ColorVisionStartup, 

so I will have to assume Spyder2. If you do not have the Startup active under

Windows, then the profile VLUT data will not get loaded, and your calibration

will not be correct. On the Mac this is less critical, as the OS loads the VLUTs.

>If I use Photoshop, there are 3 states:

>1. No ICC profile assigned to the display: this is clear, I'm working
on an uncalibrated monitor.

Photoshop will utilize an ICC profile for your display, even if it has to assume sRGB.

There is no way to really turn this off; only to bust it, by having no profiles, not even sRGB. 

You need a custom profile and its LUTs for best results.

>Photoshop and Windows built in image
viewer (which does not understand profiles) displays a given image the
same way.

Thats because they are both assuming sRGB at that point... but you are not considering

the LUTs, which get used for both color managed apps like Photoshop, and noncolor managed

ones like the Windows Image Viewer.

>2. ICC profile is assigned to the display, but colorvisionstartup.exe
is not started: Photoshop interprets the assigned pr
ofile, and
displays the images according to it.

And shows the wrong results because the video corrections have not been loaded

at startup. Wrong result, even with the right profile...

>Photoshop and Windows built in image viewer displays a given image
differently.

But both incorrect...

>3. ICC profile is assigned to the display, and colorvisionstartup.exe
is started: There is a visible difference on the whole screen when
this app starts.

Because the VLUTs have been loaded. So now Photoshop, or any CM app, will

show correct color, which they would not, in "2" above...

>PS and Windows built in image viewer are still

different to each other, but they also display images differently than
in case #2. It's like in this case, the profile is applied "two times".

See explanation above... you are only considering the profile, not the video

corrections...

>>So my question is: do I need this program at all or PS can manage the
assigned profiles alone. In the latter case: what is this application
is for?

To do a number of things, like warn when your display calibration is outdated,

but most critically to load the VLUTs on startup, which is central to color management.

I feel its necessary to comment here on the "under the hood" mentality, more common on Windows,

where users want to pull shiny parts out from under the hood=2
0and throw them away, to make 

the car lighter, so it

will go zero to sixty a fraction faster. Newer cars, and newer software, is more complex, and

do not do well with such tinkering. For instance, our Spyder2 Startup item has been replaced

with a full time utility with Spyder3, that has a long list of important tasks. But as soon as

Spyder3 was released, the tinkerers immediately began emailing me and asking if they could 

just throw it away. The answer, in a word, is NO... 

Hi,

Colorvisionstartup.exe is ColorVision's application which loads the
calibration profile into the video card. What I am unsure is if I
really need it.

If I use Photoshop, there are 3 states:

1. No ICC profile assigned to the display: this is clear, I'm working
on an uncalibrated monitor. Photoshop and Windows built in image
viewer (which does not understand profiles) displays a given image the
same 
way.

2. ICC profile is assigned to the display, but colorvisionstartup.exe
is not started: Photoshop interprets the assigned profile, and
displays the images according to it.
Photoshop and Windows built in image viewer displays a given image
differently.

3. ICC profile is assigned to the display, and colorvisionstartup.exe
is started: There is a visible difference on the whole screen when
this app starts. PS and Windows built in image viewer are still
different to each other, but they also display images differently than
in case #2. It's like in this case, the profile is applied "two times".

So my question is: do I need this program at all or PS can manage the
assigned profiles alone. In the latter case: what is this application
is for?

Sandor


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