Setting Up for Printing
Assuming you have optimised your image as a visually acceptable-looking photograph. Most inkjet printers offer an option to print in greyscale as, with a digital camera, this is a simple desaturate process. This may suffice if you need a quick greyscale print, but it will not produce the best results. Depending on your working methods, you can send the monochrome picture to your printer as a RGB file or as a greyscale. If you intend sending the picture as a greyscale image then, once you have finished your manipulations, flatten the layers (if any) before converting the image to greyscale.
Converting from RGB to greyscale mode flattens the layers automatically, but in some cases it may not apply an adjustment layer you may have made; this is especially true if you're using a Channel Mixer adjustment layer. Keeping your image file as an RGB file will give you more options to finetune the final image. Depending on your printer's driver, you may have an option to print using grey inks only or composite grey, select the ‘grey inks only' option. This ensures a cast-free photograph.
When printing black and white images, remember to let your printer know by setting the correct option in the driver. Some printer prompts, such as the HP device shown on the right, will also allow you to select grey inks.
What is a B&W Picture?
Black and white, monochrome, and greyscale are generic terms used for what we loosely call black and white photography. Black and white is, by its very name, the wrong title - almost all prints have countless shades of grey rather than the implied black and white only. Monochrome is the correct title for prints produced in the darkroom, and greyscale correctly sums up prints produced by a computer.
Due to their longer life and ability to produce stunning monochrome prints, many photographers are switching to pigment inks. However, one of the main drawbacks is a rather dull appearance when printing with glossy media. Epson introduced a Gloss optimiser ink with its R800 (A4) and R1800 (A3) printers, but neither printer has the K3 grey inks.
HP has also just launched its B9180 printer, but this lacks a gloss optimiser. Pigment ink is thicker than dye ink and sits on top of the print surface - this produces a raised image effect. This is especially noticeable on glossy media and large areas of white (paper base). Dye inks penetrate the media and do not display this effect; the HP 8450, 8750, and 7960 use dye-based photo black inks. Pigment printers work well with semigloss and matte media and produce prints that can last up to 200 years.