Photoshop greyscale conversion

I love black and white pho­tog­ra­phy. Here are some ways to con­vert color dig­i­tal images to black and white (or vari­a­tions on the theme of low sat­u­ra­tion tone) in Pho­to­shop. There are spe­cial pro­grams and plug-ins for doing this, but I find that Pho­to­shop has all the flex­i­bil­ity I need.

The sim­plest, and least sat­is­fy­ing, method of con­vert­ing a color photo to greyscale in Pho­to­shop is to choose Image -> Mode -> Grayscale. It just strips the color infor­ma­tion out of the file, con­vert­ing each pixel to a shade of grey. You have not con­trol over the process. This is not the right tool. Never use this.

A bet­ter way is to cre­ate a Chan­nel Mixer adjust­ment layer in the lay­ers palette. In the dia­log box, you can choose the per­cent­age of each chan­nel that con­tributes to the final image (it’s good to have the num­bers add to approx­i­mately 100). Play around with dif­fer­ent val­ues until you get an image you like. This is a good way to do it, espe­cially since the adjust­ment layer doesn’t change the orig­i­nal image. You can change the chan­nel mixer val­ues, or go back to color, any time you want. You can also adjust the opac­ity of the chan­nel mixer layer to desat­u­rate the image to what­ever degree you like.

Even more flex­i­ble (but more com­plex) is this method: first, cre­ate a Hue/Saturation adjust­ment layer (rename it to “desat”). Change its blend­ing mode to Sat­u­ra­tion. In the dia­log box, move the Sat­u­ra­tion slider to 0. Now the image is greyscale; big deal. But now cre­ate another Hue/Saturation adjust­ment layer under­neath the first (rename it “tone”). Play with the Hue slider. As you do, you see a dynam­i­cally chang­ing view of the image as col­ors used to cre­ate the grayscale image change. You can select for your­self the value that best brings out shadow detail or what­ever you like. If you like a toned effect (like sepia, only with what­ever tones you want), cre­ate a Color Bal­ance adjust­ment layer on top of the two other lay­ers. Try chang­ing the color val­ues dif­fer­ently for shad­ows, mid­tones, and high­lights. For exam­ple, you can have a “grayscale” image with cool darks blend­ing into warm highlights.

Very nifty.

Update 25 Feb­ru­ary 2007: As Scott Williams pointed out in a com­ment, this tech­nique is made obso­lete by the more flex­i­ble Black and White adjust­ment layer in Pho­to­shop CS3.