New IT8 target for my V750

[pherold]

The original poster was comparing an old target to one he recently received. Keep in mind that films will change color over time, which will affect the long term accuracy of using the same target and reference file.

It is possible to have IT8's custom-measured so that you can get an updated, more accurate reference. Also, some references (like Kodak's) are made in "batches" - where one reference is intended for a whole series of targets. This is obviously not as precise as getting a reference that directly reflects the colors that were measured from that target.

Information only: You don't have to buy profiling software to get a custom scanner profile - there are companies that will make scanner profiles from your scanned target as a service.

[timparkin]

I don't know if it will help but i've been going through the scanning and profiling lark with wolf faust targets and a v750 for provia, velvia and astia and I've posted a blog entry about my findings (including pictures of what things look like when you use the wrong profile). I also think I now know what different film stocks need to have different profiles.

It seems to be to do with the way the spectrum of the white light in the scanner (which is never a perfectly balanced white) reacts with the different dye pigments used in the film stock. For instance, a colour that would appear pure red when a perfect white light is used may appear magenta'ey if the light has 'spikes' in its colour specturm (e.g. if the light source had a spike near magenta and the dye didn't absorb light as well at that frequency, then more magenta would get through).

Hence, you need to create a profile for the interaction between the light source you are using and the types of dyes used in your film. This is why you can use the same profile for astia and velvia 100 when they have vastly different colour characteristics.

My posts are here

http://www.timparkin.co.uk/blog/shadow_boost_icc

http://www.timparkin.co.uk/blog/more_profiles

You should get reasonable results just using the scanner profiles I have for download (although they won't be as good as if you created your own profile, they will probably be better than just using just a kodak or velvia profile for everything)

[Peter De Smidt]

Tim,

If you look at the reference txt file for your IT8 slide, at the bottom you'll see the readings for the gray scale strip at the bottom of the chart, gs-0 to gs-23. When you do your scan, you want the black and white points to be set such that the numbers given in the scan are as close to those listed in the reference file as possible. In other words, to get the highest quality, you want the profile to do as little as possible. In particular, you want the icc file to properly map colors without having to do large luminosity/density/contrast adjustments. Once you get the scanner set such that this is the case, you ought to get a good profile, without having to mess with editing the profile, which is a bad idea.

IPhotoMinus and Lprof are free profiles creations tools. W. Faust recommended Lprof to me over IPhotominus.

See: http://www.hutchcolor.com/PDF/Scanning_Guide.pdf

[Daniel Moore]

Peter, it seems obvious to me but better to not assume, if in profile creation the black and white points are adjusted, then those adjustments ought to be applied to any image assigned that profile down the road since tones are effectively being remapped elsewhere. Is that a safe assumption?

[Peter De Smidt]

Daniel, yes, that's right. What I was talking about concerned the best way to set up the scanner for making the scan of the profile target. After that, you'd always use the same scanner settings for that type of film.

[timparkin]

Tim,

If you look at the reference txt file for your IT8 slide, at the bottom you'll see the readings for the gray scale strip at the bottom of the chart, gs-0 to gs-23. When you do your scan, you want the black and white points to be set such that the numbers given in the scan are as close to those listed in the reference file as possible. In other words, to get the highest quality, you want the profile to do as little as possible. In particular, you want the icc file to properly map colors without having to do large luminosity/density/contrast adjustments. Once you get the scanner set such that this is the case, you ought to get a good profile, without having to mess with editing the profile, which is a bad idea.

IPhotoMinus and Lprof are free profiles creations tools. W. Faust recommended Lprof to me over IPhotominus.

See: http://www.hutchcolor.com/PDF/Scanning_Guide.pdf

Hmm... I'm not sure I understand this.. I have a couple of transparencies where the black point is darker than the black point on the IT8 target. Whatever I do, if I match the target, I will end up clipping blacks. The only way to adjust the target is to tweak it some way to make it not clips. Do you have any suggestions on how to do this without adjusting the scanned profile or the data in the text file?

Tim

[dwhistance]

Tim

Have you had a look at the Hutchcolor website? He has articles about creating extended targets for those transparencies (as well as selling perhaps the best profiling targets). If you havent seen it its well worth a read.

David Whistance

[Peter De Smidt]

Yep, I agree with David. See the hutchcolor pdf linked to above.