Color Way Off

[Nick Jahn]

When scanning a 35mm negative with either Ai or HDR, the software can't seem to handle the color information. This negative is a photo of a green leaf, very close up, with a slight warm glow on one side. The software wants to "correct" the color so that it is not very green and adds a lot of red, so that the dark greens become black, some light background green becomes pink, and the medium green with the slight warm glow becomes gold. An odd thing is that if the frame for this negative is not selected in the prescan window that has many other frames for the prescan of 35mm film srtrips, the color of the leaf looks perfect. As soon as it is selected, the color goes out of wack as described above. I can correct it fairly well in curves with very radical reductions in the red and blue curves and boosting of the green curve, but the color of the frame when it is unselected still looks much better. Is this a problem with the software or is there anything I can do to have the color look correct without the radical curves adjustments that don't really work that well anyway.

I am using the latest versions of both Ai and HDR on an Epson Expression 1680 and Photoshop CS on Macintosh 10.3.5.

[LSI_Belli]

Dear Nick,

it seems that your problem is related to the removal of the orange mask.

In order to visualize the positive image of the negative, SilverFast automatically removes the orange mask based on the color information in the selected frame. However, you can manually set the thresholds applied to the histogram ("Expansion" tab).

So, lets come back to the green leaf. When you select a "close-up" frame of the green surface of the leaf, the color information available in the frame tells that there is "a lot of green", so SilverFast takes some of it away (which means the image gets magenta). If the leaf was red, the image in the frame would become cyan. That's why there is no problem with the full image frame which probably contains more color information.

To be able to select a small "monochromatic" frame, you can either:
1. select the small frame and move the tolerance slider of the automatic (which will probably not help in this extreme case)
2. or select the small frame, set manually the limits on the histogram and save the settings (for other frames)
3. or select the full frame, apply the automatic and save the settings (for other frames).

I hope it helps.

Thomas

[Nick Jahn]

Thanks for your help. Like I said previously, I can correct the prescan to get close to the true color of this extreme example where one color dominates the whole picture. But, the result is not as good as the unselected prescan, which matches a straight print of the negative perfectly. Silverfast is a great program which I have used since version 1, but some work needs to be done on it so that the software can allow for photographs that have one dominant color. By the way, I never use automatic functions if i can avoid it and I have trashed the Silverfast preferences. And I am not selecting a closeup within the frame, I am selecting the whole 35mm frame. What still mystifies me is that if the prescan frame is not selected the color is perfect, so Silverfast is able to scan this extreme one color photograph at least in the prescan phase and if it is not selected. As soon as it is selected for final scan, everything goes out of kilter.