THE PHOTOGRAPHIC HISTORICAL SOCIETY OF CANADA

The Production of Modern Digital Prints, February 15, 2006

Carson Jones from Joneshouse, Toronto

Last month we were in the 1850s learning about Ambrotypes and the new wet-plate technology that was then revolutionizing photography. Tonight we zoom ahead 150 years to another photographic revolution -- digital technology. For this talk, our guest speaker was able to bring his darkroom with him and give us a front row centre demonstration of how digital has changed the art of photographic printing. Carson's " darkroom" consisted of a beautiful widescreen Macintosh laptop, Mark Singer's digital projector, and that nearly universal tool of the modern photographer - Photoshop (CS2, the latest available).

Our talented young speaker covered an amazing amount of ground in a short time: the very basics of digital workflow, key definitions and terms, and some tried and true Photoshop steps and techniques refined from his extensive personal experience. There are many ways to use Photoshop - some more effective than others. He cautioned the audience to learn the basics and correct use, not to rely on quick fixes and shortcuts. With that in mind, Carson began a fascinating evening in the digital darkroom.

Basic Element: Carson began by displaying and magnifying an image to show the basic element of every digital image - the single colour pixel - analogous to a silver grain or dot of dye in traditional photography. The colour and luminosity of a pixel are described by numeric values - one for each of three gray scale channels representing the value of red, green and blue. 

Pixel - basic element

Bit Depth: 8 bit images have been in common use for over fifteen years. The colour and luminosity of each pixel are defined by one of 256 values for each of the three primary colours. This gives a total of 24 bits per pixel. Jpeg images, created by most digital cameras, are 8 bit images. In the last 3 or 4 years, 16 bit images have become more common. Each pixel can have one of 65,656 values for each of red, green and blue (total 48 bits). 16 bit images are saved in TIFF, PSD or similar formats. The added thousands of shades are of real benefit when editing an image. In the course of editing, image data is redistributed making the common "hills and valleys" in the histogram. The valleys represent a lack of data for some luminosity values. This may result in the posterization of smooth gradations in an image. RAW image data from a camera is in 16 bit format. If possible, one should save and work in 16 bit, only converting the final result to 8 bit if necessary for use on the web or with some editing and printing programs.

16 bit image with smooth histograms
8 bit image with hills and valleys histograms

Information: Traditional film can be measured with a densitometer and its characteristics described by a "Hurter and Driffield" curve. In digital photography the histogram takes on the job of describing the distribution of light values in an image from the darkest black to the whitest white. A eye-dropper tool is used to sample the RGB values at any point in the image. These two tools give the modern photographer valuable insights when editing an image. The histogram in Photoshop can show the red, blue, and green channels combined or separate. The eye-dropper tool can drop target spots on an image so one can see the numerical effect of image adjustments as they are made.

cause and effect - replace colour

Save the original: A photographer must protect his/her negatives. Similarly, in digital photography the RAW file or Jpeg directly from the camera must be preserved along with a version after any extensive adjustments are made. This makes it possible to replace a file damaged during editing or otherwise lost.

clever montage

Cause and Effect: Photoshop gives the photographer far more control over an image than traditional processes. Tools such as levels or curves can quickly correct broad image defects. Even individual colours or bands of colour can be selected and replaced. However, great care is necessary since this approach can affect other parts of a picture that include some of the changed colour in a blend. Each adjustment destroys some of the information contained in the original file. The more you fix an image, the more you lose information in the image. 

typical kid smile...

Montage: Combining images has been a common practice for many years. With digital photography this is much easier, faster and far less obvious. Carson showed a few examples noting that in an hour, he could do a better job with digital than he could in days with traditional processes. Colour correction, sharpening, and shadowing can quickly be adjusted, hiding the fact that an image was modified. Carson has worked with files ranging in size from around 100 megabytes to almost 5 gigabytes (which takes considerable computing power).

.. and some digital dentistry

Plug-ins: Photoshop is an open architecture to the extent that anyone can create small programs to add features to its menus and perform functions in a way not offered directly. Some are useful, but many just add a simple interface and convenient sliders to let you do what can be done directly. Reviews and user commentary on the web will let you do your research before investing in a plug-in. Many plug-ins offer a free trial period so you can try them in your environment. Carson's preference is to spend his money on good books rather than plug-ins. He demonstrated the alternatives by using a plug-in to convert an image to gray scale, then doing a similar conversion using native Photoshop layers and filters.

demo of a plug-in for monochrome
and use of native Photoshop tools for monochrome

Dodging and Burning: Do you remember the old half-yellow filters used with orthochromatic films to enhance the sky contrast? You can do this and other dodging and burning techniques in Photoshop. Carson illustrated a smooth way to accomplish this with a black and white landscape scene. He tackled the problem by creating a copy of the image, then adjusting one copy for good shadows and the second for a good sky. The use of a mask and a linear gradation tool merged the good sky with the good shadows. A radial gradation made it easy to improve the contrast in local areas by selectively combining the two images. This technique makes a much smoother blend than would be possible using a marquee to select an adjustment area. 

c1930s filter for orthochrome film

Optimizing for Print: Setting the black and white values to a few points inside the maximum values of 0 and 100 percent avoids blocking up shadows or blowing out highlights in the printed image. This may make the image look slightly worse on the monitor, but it will appear better in print. Carson demonstrated how to do this using the information palette and eye-dropper tool as a densitometer. The threshold layer helps find the darkest shadow and brightest highlight, then an information anchor point can be dropped to monitor these values once the threshold is removed and a levels layer opened so the output slider can be adjusted appropriately. The print copy of the image is cropped, sized, and sharpened as a last step before printing.

using Photoshop to adjust a landscape image contrast
landscape image before correction for contrast

Sharpening: An important part of the digital imaging work flow is image sharpening. By its very nature a digital image is originally slightly soft. The sharpening increases the contrast along contrast edges to make a crisp and snappier image. Sharpening is often done twice in the workflow. First to sharpen the image. often a localized sharpening such as the eyes of a portrait and near the end on the print version of the file as part of the prepartion to print. For intial sharpening, Carson showed how to use the high pass filter and multiple images blending the layers with the soft/hard light or overlay option. Once blended, a mask and the radial gradation tool select areas such as eyes to be sharpened. The sharpening gradually blends back to the unsharpened areas without the usual sudden changes in the image. Smart sharpening in the CS2 version of Photoshop lets one target highlights or shadows which minimizes the risk of adding shadow noise when sharpening an image.

these old eyes need sharpening

Archiving: This issue is so important to the digital photographer. The "digital negative" must retain the maximum amount of information with the widest possible colour gamut in anticipation of future improvements in printing and viewing technology. The durability of the chosen image format is another consideration. File formats fall out of favour ending up unreadable with newer software. The archival file must be saved in a format and colour space most likely to be readable in the future. This is especially important at this time with the arrival of a number of camera specific RAW file formats. Some camera makers have already dropped earlier RAW formats making it likely fewer programs will read the discontinued format in future. The venerable TIFF is a possible option having survived and evolved for many years. Adobe are promoting their DNG format while there is a movement afoot to establish an open source option not controlled by any one company (openraw.org). Open source provides specifications to all interested companies so they can write programs that will read and edit the format.

Carson used the Mac Colorsync utility* to show the colour capacity of the various popular gamuts, ProPhoto being the widest gamut presently in use.

*Windows has a similar tool called aColor Control Panel Appletfor Windows XP. You can download this applet from Microsoft. by clicking on the above name.

layers and high pass to the rescue
layer after using the high pass filter
final result with local radial gradations to allow high pass to sharpen eyes
skimpy gamut of sRGB (based on HDTV standard)

RAW Files: RAW files convey data directly from a camera's sensor with no in-camera adjustments. Each camera maker offers a program to adjust and convert their proprietary RAW file format to a common image format such as TIFF or Jpeg for further adjusting, printing and viewing. Imaging companies offer similar programs. For example, Adobe Camera RAW was first introduced as a Photoshop plug-in and is now included with Photoshop as a separate program. Camera RAW is very popular with good quality output, a comfortable interface and support for many cameras. Apple recently released "Aperture", its program intended to compete with much of Camera RAW and parts of Photoshop> At this stage, Carson felt it wasn't ready for serious commercial use (see discussions on various web forums). Adobe is currently developing a similar product called "Lightroom". The Mac OSX version is now in beta testing. Lightroom will be released for Intel based Macs and Windows systems after the OSX version is released later this year (2006). You can see a video or download the beta version by visiting Adobe Labs. Carson's organization uses a high-end program from Capture One called C1 Pro. It is intended for fast, high quality volume work. A less expensive "light edition" is also available. See Michael Reichmann's review on his Luminous Landscape site.

huge gamut of ProPhoto
Photoshop's native printer settings

 Printers: The popular lasers, inkjets and dye-sublimation printers are being joined by more high end devices intended for fast high quality production. Some of these machines print directly to photographic paper which is then processed in the traditional manner. Like many digital experts, Carson recommends you stay within one manufacturer's product line for best image life - printer, paper and ink. Today, some makers such as Epson claim an image made with their inks and papers will last over a century.

 Various software is used to pass the digital file to the printer including Photoshop and programs and drivers provided by the printer manufacturer. Separate raster image processor (RIP) programs offer even finer printer control. Excellent applications exist for printing black and white images on an Epson without colour fringing. Note: If you use Windows, check out Qimage which is an excellent program for high quality printing, including batch processing.

 If you want more information on modern printing and using Photoshop, Carson plans to have an expanded support section on his Joneshouse web site beginning March 2006. It will include recommended books, plug-ins, and detailed tutorials on using the techniques he described tonight plus much more.


Thanks to Carson Jones for permission to show some of his slides on this page. The images were taken with a Sony F828 directly from the screen. Projection with a digital projector resulted in somewhat lower resolution and some colour casting in the images. Adjustments were made in Photoshop CS2. Contents and images are ©2006 by their respective owners. The PHSC images may be used freely provided the source is clearly indicated. Contact PHSC if you would like more information on the items discussed on this page.

Click on most of the small images to see a larger version in a separate window.

Bob Carter

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