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Digitizing Color Negatives with a DSLR
Tanuki
Registered Users Posts: 184 Major grins
Please also see my other post for Digitizing Slides with a DSLR.
[Edit to add this short version of the story: You can get good results with a copy lens if you use three layers of blue gel (tungsten to daylight) over your light source, shoot in RAW, import to Photoshop, invert, then use Levels to set your white/gray/black points.]
The major challenge to digitizing color negatives, is that they have a strong orange cast. Film scanners are designed to be able to compensate for the orange cast. But if you use your digital camera and properly expose for the red channel, you'd find the green channel would be somewhat unexposed and the blue channel would be very unexposed.
You can see what I mean below with a straight capture using a tunsten light source and Tungsten WB, which I then exported to Photoshop Elements, inverted and adjusted levels on individual channels (all done in 16 bit). It was the best I could do considering the blue channel was so clipped. At 100% crop, it looks downright awful.
I tried again with the same capture, but this time I set the white balance as low as it would go in Lightroom (2000K, to be exact) before exporting to Photoshop Elements. The new results are below.
These results are much better, but the blue channel is pretty noisy because it was so underexposed.
So how can this be done better? Well, in a color darkroom, the orange cast is compensated by applying color filters in the enlarger head to adjust the intensity of the red, green and blue components of light. So I would expect that I could use a color enlarger head as my light source instead of my bare tungsten light and get better results.
But I don't have a color enlarger and I wouldn't want to go to that trouble anyway. I was thinking that I could build a DIY light box for color mixing, but then an easier solution came to mind. Maybe I could get my light balance close enough by just using some layers of Tunsten -> Daylight gel over my light source. It's cheap and easy, and it just so happened that I had some handy.
As a test, I took a photo of the unexposed leader from a roll of Kodak Gold 200 (I know, I know, it's the cheap stuff) with a gelled tunsten bulb and, no surprise, found that it just wasn't nearly balanced. I tested multiple layers of blue gel until I found that 3 layers gave the best results on my camera's RGB histogram.
Here is the result.
I think it's a pretty good result, and there's room to play in Photoshop to make it pop, whereas the 2000K version will be limited by the noisy blue channel.
Any comments, questions or critique?
In theory you could apply this approach to a point and shoot camera. But since color negatives are so thin, you have to spread the levels pretty wide and you're likely to get a lot of posturization.
By the way, I did not apply any sharpening or noise reduction in Lightroom or in Photoshop Elements for any of these images. [Edit: Correction... I did use sharpening (25% in LR) and color noise reduction (25% in LR), but no luminance noise reduction.]
For you Lightroom folks out there, I should mention that I tried to find a way to do this completely within Lightroom by using a hacked custom preset for creating a negative tone curve, but the problem is that some color channels are thinner than others, so Photoshop Levels really is the right tool for the job in this case. Maybe when Lightroom 1.1 is released there will be some new functionality that will make it possible, but I doubt it.
[Edit to add this short version of the story: You can get good results with a copy lens if you use three layers of blue gel (tungsten to daylight) over your light source, shoot in RAW, import to Photoshop, invert, then use Levels to set your white/gray/black points.]
The major challenge to digitizing color negatives, is that they have a strong orange cast. Film scanners are designed to be able to compensate for the orange cast. But if you use your digital camera and properly expose for the red channel, you'd find the green channel would be somewhat unexposed and the blue channel would be very unexposed.
You can see what I mean below with a straight capture using a tunsten light source and Tungsten WB, which I then exported to Photoshop Elements, inverted and adjusted levels on individual channels (all done in 16 bit). It was the best I could do considering the blue channel was so clipped. At 100% crop, it looks downright awful.
I tried again with the same capture, but this time I set the white balance as low as it would go in Lightroom (2000K, to be exact) before exporting to Photoshop Elements. The new results are below.
These results are much better, but the blue channel is pretty noisy because it was so underexposed.
So how can this be done better? Well, in a color darkroom, the orange cast is compensated by applying color filters in the enlarger head to adjust the intensity of the red, green and blue components of light. So I would expect that I could use a color enlarger head as my light source instead of my bare tungsten light and get better results.
But I don't have a color enlarger and I wouldn't want to go to that trouble anyway. I was thinking that I could build a DIY light box for color mixing, but then an easier solution came to mind. Maybe I could get my light balance close enough by just using some layers of Tunsten -> Daylight gel over my light source. It's cheap and easy, and it just so happened that I had some handy.
As a test, I took a photo of the unexposed leader from a roll of Kodak Gold 200 (I know, I know, it's the cheap stuff) with a gelled tunsten bulb and, no surprise, found that it just wasn't nearly balanced. I tested multiple layers of blue gel until I found that 3 layers gave the best results on my camera's RGB histogram.
Here is the result.
I think it's a pretty good result, and there's room to play in Photoshop to make it pop, whereas the 2000K version will be limited by the noisy blue channel.
Any comments, questions or critique?
In theory you could apply this approach to a point and shoot camera. But since color negatives are so thin, you have to spread the levels pretty wide and you're likely to get a lot of posturization.
By the way, I did not apply any sharpening or noise reduction in Lightroom or in Photoshop Elements for any of these images. [Edit: Correction... I did use sharpening (25% in LR) and color noise reduction (25% in LR), but no luminance noise reduction.]
For you Lightroom folks out there, I should mention that I tried to find a way to do this completely within Lightroom by using a hacked custom preset for creating a negative tone curve, but the problem is that some color channels are thinner than others, so Photoshop Levels really is the right tool for the job in this case. Maybe when Lightroom 1.1 is released there will be some new functionality that will make it possible, but I doubt it.
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