Saturday, July 12, 2014

Photivo Rocks Your Film Scans


Smena Symbol Camera, Kodak ColorPlus-200, Photivo Enhanced
Ever since buying DxO Optics pro last year, I haven't used my other favourite Raw Processing Software - the Open Source Photivo - very much. The DxO Optics Pro really has the edge for Raw file processing, with it's built-in science of matching up thousands of lens-camera combinations perfectly (even for some premium compact zoom cameras). I think now, I've uncovered another job for Photivo, and decided to blow the dust off it to enhance some TIFF File film scans. I had a hunch that Photivo would work well for this, simply because it is very aggressive - and by that I mean that just a very small tweak on certain adjustable parameters can make a huge enhancement to the photo. As I had discovered quite awhile ago, this applies to TIFF Files almost as much as the Raw files from a digital camera. After comparing some results, I'll explain what TIFF and Raw are, and talk about the difference between the two.

The first image above is a TIFF scan from a negative, using my Epson V500 Flatbed Scanner, followed by some enhancements using Photivo. For comparison, here is the original scan:

Smena Symbol Camera, Kodak ColorPlus-200
Finally for the sake of interest, here is another scan of the same Negative, done by Walmart using their professional Kodak Pakon Scanner, and loaded on a Photo-CD:

Smena Symbol Camera, Kodak ColorPlus -200, Kodak Pakon Scanner

I have to admit, the Photo-CD version came off quite a lot better than my own effort using my Epson V500, but the downside is that when Walmart gives you Photo-CD files, they're very small JPEGS that, while looking great on-screen, would not be big enough to make a print bigger than 5x7. I will also mention that I could see no sense in trying to use Photivo to enhance the Photo-CD JPEG, because JPEG files simply don't provide enough data latitude to make adjustments, and so I only did what makes sense, to make enhancements to my own Scanner's TIFF File output.

As you can see from the first picture, the results are quite spectacular. Photivo is by far the greatest Software I've used for bringing out Local Contrast without destroying colour.

Now, let's do the Tech-Talk. What I'm really doing here, although I've referred to it as "enhancement", it's not really that at all. In a TIFF (or RAW File), the pixel data is all there, but a direct to JPEG scan, or usually a straight from camera JPEG, does not do enough Data Mining to bring out the tremendous potential of the local contrast that can be available. "Local Contrast" simply explained, is the total range from light to dark available as uncompressed data at each individual Picture Element (Pixel). Still confused? Well, think of "contrast", which is the range from light to dark available throughout the entire picture in one shot. A typical JPEG file allows for some adjustment of this ordinary picture contrast, but local contrast, at the individual pixel level, is locked in. However, with a TIFF or a Raw file, it is not locked in; the required data is all there, and can be manipulated. So then, when I used Photivo to manipulate the Local Contrast within my scanner's uncompressed 16-bit TIFF File, I was able to really bring out the shades of light and dark, and the richness of colours within every single leaf of the wild-flowers, every pebble in the foreground of the rail-road, and all the nuances of reflected light on the upright metal pole of the signal light. Once I got all of this looking the way I liked it, I then "exported" the result to a compressed 8-bit JPEG File. The data is now locked in after I made the adjustments.

Take note of the words I put in bold here. TIFF and Raw Files are uncompressed, meaning that every computer number that makes up pixel information is 1:1 (one for one), and can therefore be worked on individually with various software products, giving the ability to make super-fine and wide-ranging adjustments without ruining the picture. They also have a 16-bit colour depth, meaning that 65,536 computer number possibilities are available to be manipulated for each separate base colour of Cyan, Magenta and Yellow, as well as (again separate) Gray Tones from black to white. The flexibility is enormous, but the resulting file sizes are also huge - typically 25 MB for each image file. Now, compare this with a JPEG File, where the computer numbers are 1:variable, meaning that each pixel location cannot necessarily be worked on individually, but only in pre-determined groups. Also, the colour depth for JPEG is 8-bit, which means that only 256 computer number possibilities can be manipulated for each separate CMY colour channel, plus the grey scale from black to white. This is actually plenty for the human eye, which is the reason when I convert the uncompressed image to a compressed JPEG, it looks the same on a computer screen (note- it's not the same on a printer output - if it's going to be printed, be sure to keep a copy of the TIFF File). However, to perform the kind of "data-mining" involved in extracting local contrast, a computer needs a lot more than 256 values per colour to work with, which is the same as saying even though our eyes can't always see the difference, a computer can. However, a JPEG file size is greatly reduced to a much more manageable 3 MB, which is almost 1/8 the size.

Now, let's get away from the technical and back to picture taking. You can see how by using an Open Source (free!) software product, I was able to create an amazingly detailed and rich-toned photo with a very old cheap Russian camera which cost me $4 at a yard sale, using not-so-great film, processed at Walmart for $5 per roll (CD included!) and scanned with my own consumer-grade flat-bed scanner. I also showed how the professional grade scanner used by Walmart really does give better results than my Epson V500 Flat Bed, (and BTW, these Kodak Pakon scanners are starting to show up on Ebay for $300 or less, as film photo labs are starting to go out of business).

You're more likely shooting digital, not film. Once again, the same thing applies - get a camera that shoots Raw Files and use it in Raw Mode. Raw and TIFF are quite similar, but Raw has several advantages over TIFF which I won't get into. Please do not make the mistake of thinking that by manipulating things like Local Contrast, which you can't do with JPEG files, you're somehow altering the photo. Somebody actually said to me "I don't want to make any changes to the photos I take", thinking themselves to be some kind of a "purist". Some truly great pro film photographers from the past would give specific instructions to their darkroom tech to "not change anything - if it's too dark or too light, I deliberately made it that way". This is valid in the case of these old-school and famous professionals, but it's not valid for anybody today. With digital, or even as I've just demonstrated, with colour film, after you've clicked the shutter, you're only half done the job. There is so much left to do on the computer, because there's so much detail still available that a computer can "see" but you cannot. By manipulating an uncompressed image file, you're not changing anything, but rather, you are bringing out the stuff that is hidden before printing your final product.

And remember, when manipulating Raw or TIFF Files, you are in total control - you can change things as much, or as little, as the software application will allow you to. The computer is your "digital darkroom".

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