Follow-up, scanning color negatives as color positives ...

[dmr]

The thread on difficulty scanning "thick" color negatives and the fun we've had scanning B&W negatives as color positives got me thinking ...

Most of what I scan is color negatives, and for normal or even slightly overexposed negatives shot in normal light I've always been happy with the scans.

However, I really like shooting in low light and lately when trying out the Walgreens/Agfa 400 film, there were some shots which I liked, but really didn't like the way the color came out, tending toward green with bizarre blues.

Anyway, just for giggles, why not try rescanning one of those as a positive and see if something more pleasing can be obtained.

The left one below is a rescan of a shot that never looked right to me. It always tended toward green, but I played with levels to get more of an overall warm cast. The sky still looks unnaturally blue. This was twilight on a rainy day, with a yucky grey afterglow. The left one is fixed about what I consider optimum, which is still not the way I remember seeing it. I've played quite a bit with levels on this one, but I could never get it exactly right.

The center one is scanned as a positive with invert only. Yes, it's very weak in this state, but it looks much closer to what I remember it actually was like.

The right one is an adjusted one that looks closer to what I remember, still tending toward a warm cast, and with more normal contrast. Blue was still the most difficult to work with, and adjusting the curve the way I would think would be best results in a bizarre overstated blue. However ...

Conclusion ... I think this technique, scanning as a color positve, is promising for all kinds of difficult negatives that just don't seem to give what you want when scanned normally as a negative.

 

[ed1k]

The blue image in the middle lets me guess you scanned it with autoexposure on. For difficult negatives it is not bad idea to scan as positive, but with manual exposure. You'll have to go to exposure tab and play a bit with RGB sliders to get histograms of every channel approximately in the same spot (one under each other) and of course it sould be in the middle of range. Then after inversion you will have image which require just a little ajustments like levels for red, green and blue channels.
Hope this helps.
Eduard.

 

[T_om]

Here is my shot at it. I started with the "Blue" image in the middle. The problem is the mixed lighting sources, not the scanner.

Tom

 

[dmr]

Here is my shot at it. I started with the "Blue" image in the middle. The problem is the mixed lighting sources, not the scanner.

Yours is actually closer to what I think I should see, except for the unreal blue in the sky, which really wasn't there. It also looks like you did some unsharp mask or something. 🙂

That center blue scan above was with autoexposure off. The strong blue is actually the inverse of the orange mask on the color negative, and it goes away with the level correction.

 

[normjackson]

In Photoshop selected the bluish colour cast from left of picture with eyedropper; created a new layer with this blue colour; inverted new layer to make it orange; set the blend mode of this layer to colour burn. It seems like a fairly good place to start from.

 

[ed1k]

The strong blue is actually the inverse of the orange mask on the color negative, and it goes away with the level correction.

Yes, I know. If you look at exposure tab you will see green histogram shifted left, and blue histogram shifted left even more. This is because of orange mask. When you select "negative" it tells scanner software to adjust channels in order to compensate the orange mask. When you select "positive" you'd better to compensate for orange mask manually, changing green to +0.8 and blue to +1.6 for example. Otherwise you can severe cut off the blue channel and you won't be able to get normal colours in photoshop. Though some negatives have all 3 channels in a range of ADC with default exposure settings for positives (slides don't have mask).
I think dark blue sky is because of mixed light sources as Tom mentioned. You can easily correct that with Photoshop - but this out of the "scanning technique" scope.
Eduard.

 

[Jochan]

Tom did a good calibration on the shot. And, he told the true, it is mixed lighting problem not the scanner problem. I agree with that because I have experience on making color prints in darkroom by traditional optical enlarger. You will have the same result as making the print in darkroom, nothing deal with scanner techniques.
The exaggerated blue color of the sky is caused by the color compensation against the tungsten light source. I will say this is behaviour of the film. You can’t get rid of that unless you perform partial color compensation.

 

[matti]

Is it more digital noice or grain in the dark parts of the positive scan than in the normal negaitve scan? Or am I fooled by the different color adjustments?
/Matti