How Do I Get Thee To Gray


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Ten ways to convert a color file into a black and white image. Some of these techniques allow the application to control the conversion and others cede control to the user.

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How Do I Get Thee To Gray

  1. 1. Michael E. Stern Photography/Education/Consulting In the world of pixel-based imaging the color, contrast and brightness of a particular image can vary greatly. The following tutorial is designed to demonstrate ten different outcomes for converting a file from color to grayscale (B&W). You will discover the many ways an image can change just by varying the method used for the conversion. The end results will provide you with information on how to change a color image into a black and white image. How Do I Get Thee To Grayscale? Let Me Count The Ways... Begin by selecting an image for converting. 1) Go to: Image--Adjust--Grayscale Mode a) Creates a single channel grayscale image by averaging the three channels in the RGB file. b) You’re left with limited pixel information. c) This quality compromise can show up in the output(s). d) One benefit: small file size without compression. 2) Go to: Image--Adjust--Lab Mode a) Pick the lightness channel, throw out the “a” and “b” channels and convert to grayscale. b) Same problems as above but you might be working with a more pleasing tonal quality. 3) Go to: Image--Adjust--Channel Mixer/RGB mode a) Select the channel mixer adjustment layer button first. b) Select the monochrome button at the bottom before moving the sliders. c) The idea is to have the three adjustments total 100%, but you don’t have too! d) Stay away from that constant slider unless you’re the adventurous type. 4) Go to: Image--Adjust--Gradient Map/RGB mode a) Pick black to white. Simple and mostly ineffective but hey you gave it a shot.
  2. 2. 5) Select an Alpha Channel from your RGB file a) Pick the best tonal quality from the three channels. b) Throw out the other two channels and convert the remaining channel to grayscale. c) Same problems as number 1, but you might be working with a more pleasing tonal quality. 6) Create a Hue & Saturation Adjustment Layer/RGB mode a) Drop the saturation to 0%. b) Being in RGB mode, you still have access to all of the functions, features and power of Photoshop. 7) Use a Blend Mode a) Create a new layer above the target layer or background. b) Fill with black. c) Set the blend mode to saturation, color or hue. d) Paint away on the new layer. e) Adjust the opacity setting to hold some of the original color. f) This technique is editable, fun, quick and controllable. 8) Image--Calculations/RGB mode a) Target the layer or background that you want to convert. b) target the channels that you want to use as your source for the conversion. c) You have your choice of blending modes and opacity. Oh my there are too many choices again. d) Select the “add” blend mode at 100% opacity. e) The offset and scale options allow you to fine tune the math that Photoshop uses to mix the color numbers of the pixels in the selected channels. This in turn gives you incredible control over how the gray values are created. Offset adds or subtracts brightness values to the pixels, it ranges from –255 to 255. Scale divides the combined numbers created by the target channels. Selecting “2” divides the combined numbers in half, while choosing “1” as the divider leaves the combined numbers alone. NOTE: While choosing “1” leaves the combined numbers undivided, the maximum luminance values of the combined numbers can not be greater than 255 or less than 0. f) This technique generates the optimum mixing of pixel information to achieve a quality grayscale image.
  3. 3. It takes a lot of practice to master this particular technique. Can you say no social life? g) Go ahead, don’t be afraid of this diabolical dialog box, it’s only scary the first 27 times you try it. 9) Double Hue & Saturation Adjustment Layers a) This method is so much fun you’ll forget about eating and go straight to drinking. b) With the file of choice open, make a Hue & Saturation Adjustment Layer. c) Drag its’ saturation slider all the way to the left. c) Make another H&S Adjustment Layer. Change its’ Blend Mode to “Color.” d) In the Layers Palette you now have two adjustment layers. The top most one has a “Normal” Blend Mode and it’s Saturation slider is all the way to the left. e) The lower adjustment layer is set to the “Color” Blend Mode. f) Now just move the Hue slider in the lower adjustment layer to taste. For additional fun also move the Saturation slider. 10) CS4 Black & White Adjustment Layer a) In CS4 the newest tool is the Black & White Adjustment Layer. b) With this adjustment layer open and set above the file of choice, it is simply a matter of moving the sliders, selecting a preset or clicking on any part of the file and dragging left or right. This is fun and endless so get plenty of rest and bring lots of water, you may not come out for days.
  4. 4. Good luck! Michael 626-298-6747