The Digital Eye Colorizing a Black and White Image Adding color to a black and white image can transform a snapshot into a masterpiece in a few easy steps. By Stephen Romaniello Colorization of both still and motion pictures has been around for a long time. Early movies were often hand painted frame by frame to produce colorful artistic effects as can be seen in the work of George Mélies (Figure 1). Hollywood has digitally colorized numerous movies that were originally filmed in black and white since the 1970s and hand coloring of still photos has been practiced almost since the inception of photography. Back in the day, years before the invention of color film, it was a common practice to hand tint photos in an attempt to create more realistic images. The first examples of hand- colored daguerreotypes were made by the Swiss painter and printmaker Johann Baptist Isenring, who used a mixture of gum arabic and pigments to color daguerreotypes shortly after their invention in 1839. Colored powder was fixed on the delicate surface of the daguerreotype by the application of heat. Later, hand- coloring was used with other types of photographs like albumen and gelatin silver prints. Though hand- coloring was invented in Europe, the technique gained considerable popularity in Japan, where the practice became a respected and refined art form beginning in the 1860s.
Figure 1: A 1902 hand- colored frame from George Mélies film Le Voyage dans la lune The golden age of hand- coloring was between 1900 and 1940 when it was quite fashionable to give hand colored portraits as gifts for special occasions. By the early nineteen fifties the introduction of color film had dramatically decreased the demand for hand- colored photos and their popularity rapidly declined. Happily, the digital coloring process has seen a revival of the art of hand coloring due to the great potential it affords. Image Capture The colorization process of still images actually begins during scanning. Instead of scanning an image as a grayscale, it can be scanned in RGB mode. Although there is no significant difference in the appearance of the RGB image from the grayscale, it has the potential of supporting color. If the image has been scanned as a grayscale it can be converted in Photoshop by choosing Image > Mode > RGB Color. When a selected area of an RGB image is colorized, its gray pixels are converted to colored pixels. Gray pixels have RGB values that are equal. For example, the RGB values for black are red = 0, green = 0, and blue = 0. The RGB values for white are red = 255, green = 255, and blue = 255, and the RGB values for medium gray are red = 128, green = 128, and blue = 128. When a group of gray pixels is colorized, the red, green, and blue components are remapped to disparate values.
When the Colorize box on the Hue and Saturation panel (Figure 1) is checked, hue, saturation and brightness values of the current foreground color are applied to the selected area. The sliders change to represent absolute values instead of relative ones. The Hue slider reads from 0 degrees on the left to 360 degrees on the right, and the current foreground color s position on the color wheel is displayed. Figure 2: Checking the colorize box in the Hue/Saturation panel applies the current foreground color to the selected area. The Hue slider is then dragged until the area changes to the desired color. The Saturation slider reads from 0% to 100% and defaults at 25%. Dragged to the right, the slider increases the intensity of the color, to the left intensity is decreased. By default, the Lightness slider displays relative values between 100 (black) and +100 (white) and will darken or lighten the area if dragged to the left or right respectively. Working with Photoshop s Hue/Saturation properties on the Adjustments panel assigns the values to an adjustment layer that has several advantages over the old Hue/Saturation dialog box. First, colorizing on an adjustment layer enables subsequent editing at any time. Also, a layer mask is automatically created based on the selected area. The white areas of the mask reveals the adjustment and the black areas conceal the adjustment so that the color can be isolated to a specific shape and location. Furthermore, all the advantages of layers are available including opacity and blend modes that can mitigate or enhance the layer s color.
Let s go through colorization step-by-step so you can get the hang of how it operates. The process itemized here uses adjustment layers and is the most efficient method of colorization. Figure 3: The original black and white image. Colorizing the Bottle 1. Open the document to be colorized. (Figure 3) 2. Choose Image> Mode >RGB to convert the image into a file that supports color. 3. With the lasso tool, select an area. In this case it s the bottle that the girl is holding. 4. On the Adjustments panel, the Hue/Saturation icon is clicked to display the Hue Saturation controls. A new Hue/Saturation adjustment layer is created. 5. When the Colorize box is checked the bottle turns red - the current foreground color. The Hue Sliders are dragged to produce a green color. In this case, the hue slider is dragged to a value of 145 degrees and the saturation slider is dragged to 25 percent. 6. Observe the layers panel (Figure 4). A new adjustment layer has been created with a white area in the shape of the bottle that reveals the colorization and a black area surrounding the bottle that masks the color.
Figure 4: A new adjustment layer has been created with a layer mask. The white area reveals the Hue/Saturation adjustment and the black area masks the area around the bottle. 7. Next, the girl s face is selected with the quick selection tool. 8. Again the Hue/Saturation icon is clicked. The colorize button is once again checked, and the Hue slider is dragged to 26 degrees and the Saturation slider to 24 percent. (Figure 5) Figure 5: The face is selected and a new Hue/Saturation adjustment is made applying flesh tones. 9. The layer mask thumbnail is selected and the girl s eyes are painted with black to mask the whites of her eyes back to grayscale. (Figure 6) Later a separate adjustment layer will be made to colorize the pupils.
Figure 6: The eyes are masked from the adjustment so the whites appear neutral. The pupil will later be colorized on a separate adjustment layer. 10. With the layer mask still targeted, the hands are painted with white to reveal the Hue/Saturation adjustment. Pressing the X key toggles back and forth between black and white by to speed up the process as the mask is applied. (Figure 7) Figure 7: The hands are unmasked by painting white on the adjustment layer to reveal the fleshtone. Ruby Lips 11. The lips are selected. Once again the Hue/Saturation icon is clicked to display the controls. The Hue slider is dragged to 11 and the Saturation to 27- a reddish color as in Figure 8. Figure 8: The lips are colored red on a new Hue/Saturation adjustment layer.
12. A 40 pixel soft brush with the opacity to 15 percent is chosen. White is painted on her cheeks to create a soft, rosy complexion. It s critical that the lips layer is located above the flesh tone layer to be visible. (Figure 9) Figure 9: The color of the lips is applied with white and a low opacity brush on the layer mask to create a subtle, semitransparent rosy complexion on the face. This layer has to be above the flesh tone layer in the stack in order to be visible. 13. The rest of image is colorized in this manner by selecting each component, the sweater, collar, hair, eyes, ring, note and background and creating a specific Hue/Saturation adjustment layer for each color. 14. Soft or ambiguous transitions between colors can be refined by painting on the edges with a soft brush. (Figure 10). Figure 10: Subtle transitions between colors are made with a soft brush. The Finished image is shown in Figure 11. One major advantage of the adjustment layer technique is the ability to easily and quickly create multiple versions of the
picture. All it takes is duplicating the image (Image> Duplicate) and a click on any of the Hue/Saturation adjustment layers to display the controls. Dragging the sliders produces different colors for that layer and a new look for the duplicate image as illustrated in Figure 12. Figure 11: The finished fully colorized image. Figure 12: A second version is easily created by duplicating the image (Image> Duplicate) and dragging the Hue/Saturation sliders on each layer to change the colors.