Imaging the Natural World

Color Gamut & Fine Art Media

In conversations with my students and browsing the Internet, I find an abundance of worshippers who believe the holy grail of ink jet media is the one with the widest gamut. Choosing the very greatest gamut and forsaking all other considerations is certainly a choice that one can  make and perhaps someday compromises will not have to be made when setting sights on this goal.

I personally like the look and feel of fine art media for many of my prints and don’t want to avoid using it for the sake of greater gamut.  It is true that the gamut is an inherent property of the media for a given ink set and printer and there is nothing you can do to materially increase it.  That does not mean that you must accept the “flat” look or “lack of punch” that is often associated with the fine art media.

I have discussed this with many printers. They send their image to one of the wide gamut photographic papers and to a fine art paper and are terribly disappointed in the results on the fine art media. This is an unrealistic comparison because  the fine art media will definitely “:dumb down” the look of the print. It simply accepts ink differently. So there are two things going on in the fine art print, the smaller gamut and the distinctly different inking properties. I believe these two are lumped into one when the fine art media is dismissed out of hand.

There is a solution, and of course it does entail some more effort. The solution is to use the soft-proofing capabilities of Photoshop and to make further adjustments to your image before printing. These adjustments are specifically to accommodate the media you are printing to. While you are not improving the gamut of the media, you can return the “punch” that you saw on your monitor to the print. My experience is that soft-proof adjustments for  photographic media are usually minor but for fine art media they can be extensive. 

For me, I will give up a little gamut in my images for the look and feel of the fine art media. It is a compromise that I am willing to make. Perhaps down the road, it will not be necessary and I can have the widest gamut of all media.

Contrast Masking in Photoshop

In days long gone (at least they seem so),  creating cibachrome prints from chromes often required the use of a contrast mask to reduce the over-all contrast of the image.

 

 

Occasionally a digital image can benefit from applying a contrast mask. On a trip to Mexico several years ago I captured this image of Mexican children at a festival. It was high noon under a blazing sun and no fill flash. The resulting chrome was very contrasty.

 

 

 

 

 

Mimicking the contrast masking procedure used when making prints from cibachromes I first create a duplicate of the image in Photoshop (Image->Duplicate) and arrange a tiled view of the original and duplicate image. The duplicate image is then converted to a grayscale.  (Image->Mode->Grayscale). The resulted is shown in Step 1.

 

 

 

 

 

 

 

 
Step 2 inverts the grayscale to comlpete the creation of the contrast mask as seen below. (Image->Adjsutments->Invert)

 

 

 

 

 

 

 

Pin registration of the mask and the original is accomplished by selecting the inverted grayscale image and while holding down the shift key, dragging it onto the original. The result is shown in Step 3 below.

 

 

 

 

 

 

 

 

Step 4 changes the blending mode of the contrast mask from normal to overlay resulting in the effect of applying the contrast mask as shown below.

 

 

 

 

 

 

 

 

The last step is to adjsut the opacity of the contarst mask layer to create a pleasing result. My final choice for this image was 86%. Below are the before and after images.

Image Resolution and Image Size

The question I get asked more often than any other in my digital imaging and Photoshop classes is “How big can I make a print from a file from my digital camera?” I will answer the question specifically, but first consider the factors that influence the answer to the question.

Native Resolution: This is the actual capture resolution whether by scanner or camera sensor. It is sometimes represented by file size, but specifying in terms of mega-pixels or pixel dimensions is more intuitive. In general, the greater the native resolution, the larger the size of the final printed image can be. However, it is important to note that camera sensors of the same pixel dimensions (resolution) do not necessarily yield images of the same quality. For example, sensors of smaller physical size will be more susceptible to noise than larger sensors with the same mega-pixel resolution.

Image quality: For a given “native resolution” the better the quality of the image, the more tolerant it will be to “up-sizing”. In many respects this is no different than the film world when the quality of the negative had much to do with how much enlargement the image could tolerate. Image quality depends on the quality of the equipment used to capture it, proper exposure, camera steadiness and the photographer’s technique.

Viewing distance:The distance at which a given image is viewed influences what the acceptable print resolution can be. In general, photographic prints in the traditional sizes of 8×10 to say 16×20 are viewed at roughly arm’s length or about three feet. Much larger images (panoramas often may fall into this category) are usually viewed from greater distances and may be rendered at a lower image resolution than the smaller ones.

Care in post-capture processing of the image: Even a high quality native image can be rendered unsuitable for large size prints by poor techniques durng post-capture processing. Techniques include such standards as tonal range adjustment, resizing and sharpening.

Viewer discernment: The judgment of photographic quality is truly in the eye of the beholder. For this reason alone, there is no universally accepted definition of an image resolution that equates to photographic quality. I have demonstrated this in my classes. I have shown prints of image resolutions from 180 ppi to 340 ppi. Seen individually, most students stated that they found the images of “photo” quality. However, when they see the prints together, they can easily distinguish between the one printed from the highest image resolution and the one printed from the lowest. In some cases, they can even put them in the correct order of increasing image resolution.

Image subject: This also is subjective, but the subject matter portrayed in the image can determine how large it can be printed. For example, still life photographs portrayed in an “arty” way, can sustain a greater degree of enlargement than images where the expectation of fine detail will require greater image resolution.

Media: The media used for printing can have a strong influence on the size a given digital image can be printed to. For instance, I have seen images printed on highly textured canvas that look wonderful, but fail when printed on a glossy photo paper or fine art media.

So there you have it; a lengthy list of considerations that impact the answer to the question of how large a print can be made from a given “native capture”. Now let’s talk some specifics.

 

The data in the table presents a pretty discouraging picture. It is often claimed that image resolution must be 300 dpi to achieve “photo quality”. Does that really mean that we can only print to an 8″ x 12″ with an 8.3 Mega pixel camera such as the Canon30d as the above table suggests? In my experience, certainly it does not. I routinely print images from a Canon 30d to 16×24 and, on occasion, even larger. This is where all of the factors I listed above come in to play. For instance, I have settled on 240 dpi as my standard for most of my digital images from the Canon 30D, this allows me to print up to 9.7×14.6 without interpolation (ie using the native capture).

In addition, I have found that if the original image is of high quality and I take care in post-processing, that I can up-size or interpolate using Adobe Photoshop so that the final image size is 2 to 2.5 times the native size or in the case of my Canon30d, up to 24×36. In fact I prefer these images to those from my chromes scanned at 3600dpi and printed to the same final print size. So, the numbers in the table don’t present such a discouraging picture after all!

To determine your own “comfortable” image resolution, I suggest you select one of your best digital images. Judge it by critically inspecting it at 100% in Photoshop. Print that image using several different image resolutions withoutinterpolation. Compare the images and select the resolution that satisfies your expectation of image quality. Once you have selected your personal image resolution, print the same image up-sized. Try up sizing in the range of 1.5x to 2.5x using Adobe for the interpolation. Compare the up-sized images to establish your personal limits for image up-sizing.

Determining your personal working image resolution and up-sizing limits is exercising one of the exciting aspects of digital imaging: ultimately you are in complete control of the resulting image and have no one to satisfy but yourself.