Color Correction on Multiple Images

[BradF]

NegaFix is helping me get good results for individual images, but sometimes I have multiple negatives from the same event (like a wedding) and I need the skin tones, the bride's dress, the bridesmaid's dresses, and backgrounds to match across a whole batch of images even when the lighting conditions, aperture settings, etc. varied significantly between shots. The professional labs somehow accomplish this when they deliver preview prints. How do they do that!?!?

It seems like if I put the 48-bit raw data on disk for a whole group of negatives and use SilverFast HDR and Job Management, there should be some way to run a color correction algorithm that first analyzes a group of images then optimizes each image with the color matching for the whole group in mind?

I realize I'm most likely being naive about the complexity of this task. Any thoughts or suggestions on tools or techniques to address this issue?

Thanks.

- Brad Funkhouser
brad.funkhouser@verizon.net

[BradF]

Here's a simpler example of the issue with which I'm grappling...

I have 5 images from a wedding ceremony. The images all include the same general scene but were captured with different exposure settings and from different angles. I scanned the images from medium format negatives and used NegaFix's profile for the film type to remove the orange mask and optimize the dynamic range of each image.

Each individual image looks good. But when I look at them as a group, there are significant color mismatches between pictures. Colors are slightly different for the bride's dress, the carpet, the bridesmaids' dresses, the background, etc.

I have the same 5 images as preview prints from a professional lab. The lab's images have a compressed tonal range in comparison to my scans of the negatives, but they do have excellent color matching between pictures. I don't want to rely on getting prints from the lab. I'd like to be able to accomplish this subtle color matching on my own.

I've tinkered with this situation a lot. I even got a Photoshop plugin called iCorrect Pro which lets me create "memory colors" to assist with color correction between images. It helps, but even with that I can't come close to achieving the degree of color consistency across the images that the lab produced. How do they do that? Does anyone have suggestions on tools or techniques to address this issue?

Thanks.

- Brad Funkhouser

[LSI_Wolff]

Dear Mr. Funkhouser,

One of the most important questions is how consistent are the colours of the different negatives?

If they are all from the same film (identical emulsion, ASA), AND are exposed under exactly the same lighting conditons with the same lens and filters, AND are developed with the same C-41 process, AND ? than it's more or less easy. Only the first negative has to be corrected. The saved scanning parameters can be copied (or even reloaded) to the following negatives ? without any new changes.

But!

This is of course neither standard, nor natural in wedding photography. The light changes, perhaps completly: from low-key indoor, to sunlight outdoor, to evening light, to flashlight, to mixtures of all, to? . And in addition different lenses, filters and even films are in use, ?
This all brings up different colours. And that's good! That's what makes atmosphere.

The art of the labs / the scanner operators is to manage these colours inividualy. That's what makes a lab good or not - the knowhow of there operators, there experiences and skills.

Problems occour when all images have to show the same (non natural!) colours. E.g. the white of bride's dress has to be the same over the day, under all lighting conditions. That's impossible for the "perception" of a film (although it appears possible for our eyes). But don't trust your eyes, they lie, because there nature is to work relatively and not absolutely!

I think there is no other way than to work out the best results individualy, from negativ to negative. Some help may come from saved settings and parameters but that's not the final solution your are looking for.


Best regards
Gerhard Wolff
LaserSoft Imaging AG

[BradF]

Gerhard,

I appreciate your insights. The amusing thing is that the first set of negatives I scanned were from a studio sitting where the lighting, lens, exposures, etc. were the same for every image! I was definitely lulled into a false sense of confidence.

Then when I scanned multiple rolls from a wedding, reality struck me. I now realize that I must go through the same type of process as a good lab: exposure compensation, white balance, contrast adjustment, color matching, etc.

I do believe the labs have some analysis algorithms which don't seem to be available outside of the high end processing systems or minilab systems at this point. Still mystical tools to me such as density analysis and average mean color analysis. I hope to understand their tools and techniques in more detail over time. I've been scanning reflective images for quite a while, but obviously I'm just getting started in the world of digitally processing negatives.

At some point I imagine that additional types of sophisticated analysis tools will become available to me as plugins to Photoshop or functionality within products such as SilverFast. I look forward to having the ability to rival what the lab produces.

Thanks.

- Brad