Ditgital Quality

Reprinted from the Yahoo Digital Darkroom forum.

Christopher wrote:
> Way back in the 1900's you could judge quality by looking at your
> negatives. You held them up to the light or put then on a light-
> table and if you were lucky a few of them just popped out at you.
> Then you grabbed your loupe and inspected them in detail. The raw
> negative contained everything you needed, the darkest darks and the
> lightest highlights, if the details weren't present on the negative
> they did not exist. The negative also had a dynamic range that was
> far greater than the paper it would be printed on without dodging
> and burning. If the choice negatives were sharp in the right places
> you selected them to be printed, and tried to pull of much of what
> was good about your negative onto the paper.
>
> So for me the best way to judge quality with film was direct
> analysis of the negative. So...
>
> How do I best judge quality of my digital pictures?

When shooting slides, when a highlight equaled the base density of the film, no matter what you did, you could not get any detail out of it. Gone. When shooting negatives, when you reached the base density of the film, you got a solid featureless black with no shadow detail. When shooting digital, you are shooting positives like slides, so protecting vital highlight detail is of primary importance. If your camera shows a histogram - you can immediately judge whether an adjustment is needed. More at http://www.larry-bolch.com/histogram/

A camera with a live, real-time histogram puts the best light meter ever devised into your hands. If it only available on review, then shoot test exposures to get it right, checking and fine tuning with the histogram.

Common sense must be used with histograms. Any light source in the image area, specular reflections off chrome and so on will be base density or in digital terms, 255, 255, 255. In any case there is generally a need for a bit of pure white and pure black to keep a print from looking weak or muddy. With proper exposure, you can capture the raw material to give you the best starting point when you are making the picture in processing. With proper exposure when taking the shot, you have the chance of placing your shadows and highlights when making the shot. More at http://www.larry-bolch.com/basic_processing/

Where control of processing of chromes was generally beyond the shooter, and done in photomechanical reproduction, the digital photographer has very powerful tools. The same techniques of dodging and burning are still built into image processing programs. However, by layering and masking, far more sophisticated control is available for stretching mid tones, opening shadows while still retaining highlight detail. Bracketed exposures can be layered and masked, taking the highlight detail of the most dense and the shadow detail of the lightest, using the in-between shots for a smooth transition. This can extend the dynamic range captured well beyond that of any other photographic medium. I understand that it will be automated as a feature in Photoshop CS2. The manual technique is described in an illustrated tutorial at http://www.larry-bolch.com/layers.htm


> Obviously viewing at 100% magnification on a properly calibrated
> monitor is a start in the right direction. Although Digital has made
> so many aspects of photography easier, it appears to me to have made
> the initial judgements much more difficult for me.

That is practically meaningless. Like viewing your film through a microscope. I used a 25x grain magnifier under the enlarger to achieve the sharpest possible focus in the fume-room, but it told me nothing else.

When crunched down to 300 dpi in printing, all the noise, pixels and everything else that looked horrible at 100% now looks stunningly good. The real proof of digital quality is in the print, and that is more a matter of your skills than anything else.

It takes a number of years in the fume-room to become a competent printer, and you continue to improve your skills for a life time. The digital-darkroom is not different. It does give you considerably more advanced tools, however, and it takes time to develop a feeling for their use.

Printing colour in the fume-room, I had control of only two things - colour balance and exposure. Doing a picture shot under mixed light, using two or more colour balances on a single print was excruciatingly difficult - though possible. Dodging and burning was practically impossible to do identically on two prints in succession. Both are much more easily and consistently accomplished in the digital-darkroom.

In the digital darkroom, you have control of contrast - which you had with B&W, but only in the most limited way printing colour negatives. You also have control of where you place your mid-tones, which could only be done with masking film or inexact dodging and burning. Saturation is also under your control in the digital darkroom, as is unsharp masking.

Seeing one of my exposures, you might find reason to question my camera work. They tend to be soft, dark and a bit muddy. They are soft, because I keep in-camera sharpening off. I have far better tools for sharpening in Photoshop than I have in the camera. I can come pretty close to simulating film accutance - generally defined as edge contrast - so the image looks sharp not sharpened. I protect highlight detail that I want to retain, so my exposures tend toward the dark side. I know that when I am in a situation where the contrast range is challenging, that I can bracket or shoot in RAW format and bring out loads of shadow detail and place my whites exactly where I want them.

It also comes with a lot of shooting and a lot of printing. For shooting, all the cost is up front with digital. No wasted time fighting traffic back and forth to the lab, no processing and film costs. Your time is spent interpreting the image to say what you want it to say.

You can be very selective about what you print as well. No excuse for shoe-boxes full of 4x6 prints that no one ever looks at. Triage with care, and choose only the best on the basis of content. Put the effort into making it a portfolio-quality print. Do not be impatient - it takes time and the learning never stops.

While processing, you will learn a great deal about shooting. All your errors vividly get in the way of your goals, so next time you are on a shoot, you will refine from what you have learned. Eventually, you will develop a feeling for what you want to see when you open the image file, and you will shoot for that quality in taking the picture. When making the picture in the digital darkroom, you will have the flexibility then to interpret the final result, as you feel it should be. The more you do, the more fluent you will become.


©2005 Larry N.Bolch