When creating an image for output, one must remember the old adage, “Garbage in… Garbage out”. If your digital file is not the best it can be then the resulting print will not be very good either. The larger the output the better the image must be. Many file defects can not be detected in a 4×6 inch print, but would be glaringly obvious in a 12×16 inch or larger print. If you are reading this article, one must assume your goal is a larger and better image. In many respects the quality of your digital file is the the most important factor in output.
The first step is to become familiar with your camera or digital capture device. Take the time to read and understand your camera’s owner’s manual. Be sure your settings are set on the largest image your camera can capture. It does not make sense to pay for megapixels and set your image size to small. Memory space is no longer expensive so should not be an issue. The larger the file the larger the output. If your camera has the capability to shoot in Camera Raw, it is wise to use it. If you are used to shooting in jpg and just started using camera raw, you may find your images seem flat, not as vibrant. That is because the camera applies adjustments to the jpg image. In camera raw, you must apply the adjustments. Some other advantages of using Raw are an uncompressed file, more digital information, more ability to edit and adjust the final image, and usually a larger image.
It will require some digital editing, but if your objective is to create the best possible printed image, then it behoves you to learn to edit your work. There are many factors that affect the quality of your photo. If you find you are unable to hold the camera steady – use a tripod or a monopod. If you are seeing a great deal of digital noise (graininess), lower your ISO or use a flash. Although there are software fixes for issues like digital noise, it is best to have a great shot to start rather than try to fix a bad shot.
DSLR cameras usually have a menu option for setting color space. The default is usually sRGB. The sRGB color space is the color space of choice if you only intend to post your images to the web. It is the space most computers and other devices use. However, sRGB is a limited color space, compressing colors and limiting color gamut. The most widely used color space for output is usually Adobe RGB. It has a wider gamut (more colors) and is compatible with most digital printing systems. If you set your camera to shoot in the Adobe RGB color space, you will want to use that color space in your digital editing software as well. It is not advisable to go from one color space to the other for output. By shooting in sRGB then converting to Adobe RGB in your editing software, you might find a drastic difference in color appearance. If you are using Photoshop for your editing software, you can designate your color workspace. Go to Edit> Color settings and select Adobe RGB for your working space. Under Color Management Policies it is a good idea to choose to “Preserve Embedded Profiles” and to have Photoshop ask if there are profile mismatches. I do not change the color space if there is a mismatch for the color space as it changes the colors. If your camera does not have a setting for color space, it is best to assume you are shooting in sRGB.
Image resolution is another concern when thinking about image output. Resolution can be very confusing as it refers to several very different things. There is first the image resolution – how many pixels per inch in your digital file. There is screen resolution, the pixels per inch on your computer screen, and finally there is print resolution- how many points per inch of ink the printer puts onto the printed media. All of these measures of resolution are different but are often confused. For this part of the discussion we are mostly concerned with image resolution. The image resolution is directly correlated to your image size.
I often hear and see the concept that to be printed an image must be 300 ppi (pixels per inch). If one is planning on outputting to a published source – newspaper, magazine, etc., that is correct. The publishing industry maintains a standard of 300 ppi and if an image is sent in another resolution it will become a different size when placed into the publisher’s document. For consistency and convenience published material should be submitted at 300 ppi. Often images published in newspapers and magazines are small. Meeting this size requirement is not difficult.
The 300 ppi publishing rule does not have to correlate to image printing, however. If the image is good, it can be printed with its native resolution to whatever size it continues to look good. I have read numerous articles about what resolution the image file must be in order to have a great print. Despite what many “experts” say, in my 10 years as a commercial digital printer I have printed images at 72 pixels per inch resolution that look as sharp or sharper than images printed at 300 ppi.
The major factor here is “native resolution” – The actual pixel size that your camera captures. When you import or download your image from your camera to your software it is the pixel dimensions set by the image sensor of your camera that dictates the resolution size, and not the other way around. That is the resolution does not (within parameters) dictate print size but the print size dictates the resolution. Consider the first image size box. The native resolution of this image is 5616 pixels x 3744 pixels. By resizing the document size resolution I can change the image size output. If I wanted to print this image at 8×12, it would increase the document size resolution to 468 ppi but not alter the native resolution of 5616 pixels x 3744 pixels. If my original image is sharp at 100% view in Photoshop, it will print sharp at 12×8 or 23.4×15.6 or even 78 x 52 at 72 ppi. (One thing to note is that at the smaller sizes the printer device will eliminate pixels but it done by algorithms and is invisible to the user). The images of the daliah above would print fine at 72ppi with the native resolution, but as you can see would print badly at 72ppi when up-resed.
If you decide to up-res an image (add pixels) then you are changing the native resolution and your image will begin to degrade to the point where it is often destroyed or at the very least quality compromised.