and they always will. It’s an unavoidable reality.
The reason for this has little to do with color management, inks, paper surfaces, device profiles, or any other adjustment-related issue. The simple fact is that your monitor’s white is illuminated by a projected light source and the white of your paper print is illuminated by reflected light. This tone range difference takes its most egregious toll on the darker parts of the image; the three-quarter tones. The very tones that get slighted by your camera’s image sensor are the most vulnerable in print.
As I often claim, detail is a product (result) of contrast. Contrast is the measured difference between two tones. On the printed page, this statement has to be further clarified… detail is determined by the perceived difference between two tones. Here’s the visible proof behind the statement.
Consider the visual extremes (white vs. black) of both of these media vehicles- paper and the computer display. In the case of pictures in print, the white of the printed substrate (usually paper) is determined by the whiteness of the paper and the strength of the light reflecting from the unprinted part of the paper. The darkest color (usually a multi-color, composite black) of the print is determined by the density (or light-absorbing) opacity of the colorant (usually ink).
The computer display plays the contrast game by a completely different set of rules. While the black of the monitor does have its opacity limitations, the white illuminate of the display is limited only by the brightness of the (typically) LED (light emitting diode) elements; which in turn are affected by the brightness or gain dialed in by you, the user. Brightness directly affects contrast. With more light comes more potential contrast, and where there is contrast, there is detail.
Which system do you suppose displays the most contrast? Duh!
As a color separator in the litho trade, I faced this same type of problem when reproducing images from photographic prints versus photographic transparencies. It was always easier to capture detail from a transparency than from a print. In technical terms, a printed page typically measures a reflective contrast of 1.7 points of density, while a transparency can display upwards of 3.8 points of density, depending on the strength of the backlit light source. More dynamic range produces more steps (bits in digital lingo) in the tonal scale and thus more detail. With digital images, the spread is even higher. When prints are compared to LED displays, the contrast ratio is huge on the display but remain the same for print.
You simply cannot pour enough light onto a page to bring the reflected brightness to the level of a projected display, just like you cannot dial down the brightness of the display to match the normal contrast of a printed picture. It’s apples and peanuts anyway you “look” at it. The two methods of viewing a picture are simply, fundamentally, and totally different.
THIS is why you can see detail in the darker portions of a displayed image that you just cannot see in the printed version of the picture. The contrast ratio visible in print is simply not in the same league as your backlit computer display. It is woefully insufficient.
So, what can be done to close this light range gap? Can you do anything to improve the detail in the darker portions of the image? Absolutely. But you must 1) recognize that this issue exists, and 2) you must learn how to effectively compensate the tonal range for the difference. You can make a significant difference in your printed images by taking the same actions that we litho folks have done for decades… you have to learn to shape the internal contrast of the images before they go to print.
Remember that camera image sensors record light linearly, one photon at a time, but your eyes/brain perceive light quite differently. Camera images record light with a serious bias toward the lighter side of the tone scale (an area we call quarter tones), while recording very little data in the darker portion of the tone range (the three-quarter tones). The result in print is almost always a lack of detail in the darkest parts of the image. When this lack of data is combined with the print’s lower contrast ratio, shadow detail takes the hit.
Learning to adjust your images to print all available detail is critical for serious photographers. Pay attention to separating tones in the darker parts of the image where detail can be buried when printed. This is a topic that I will cover in upcoming sessions of the Tonality and the Histogram series. If this post makes sense, and you want to learn how to bring out detail in your images, follow this blog and learn more. If you have friends who can benefit from this information- forward the address of this blog to them and help spread the word about this free resource. I’ll most certainly appreciate it!
If you really want to get serious about printing image detail, I am releasing an ebook/iBook that hammers out the specifics about this critical topic very soon.
Anyhow, that’s the way eye sees it.
See you next time.
If you have an iPad and want to learn more about controlling color and shaping tonality in your images, my totally interactive Accurate Color iBook will answer many of your questions: