Chapter 6
Figure 6-1 The combined number of bits determines the shade of gray.
Figure 6-2 Each pixel in a digital image consists of a color value for red, green and blue, where the bits make up the color values and the bits are grouped into bytes for storage on a computer.
Figure 6-3A illustrates the image quality of a fingerprint at 1200 pixels per inch (ppi) when zoomed into the image.
Figure 6-3B illustrates the image quality of a fingerprint at 600 pixels per inch (ppi). (Notice the difference in contrast between the fingerprint image at 1200 PPI when zoomed into the image.)
Figure 6-3C illustrates the image quality of a fingerprint at 300 pixels per inch (ppi). (In addition to the visible difference in contrast, it is now easier to visualize the individual pixels when zoomed into the image.)
Figure 6-3D illustrates the image quality of a fingerprint at 150 pixels per inch (ppi). (In addition to visualizing the individual pixels, there is a significant degradation of image quality and loss of detail when zoomed into the image.)
Figure 6-4 Bits are grouped into bytes, and bytes are grouped into kilobytes, megabytes, etc.
Figure 6-5 This figure illustrates an image with a portion greatly enlarged, in which the individual pixels are shown as little squares.
Figure 6-6 When compressed images are displayed in a small space, the loss of data from the compression process is not readily apparent.
Figure 6-7 When compressed images are decompressed and zoomed in for purposes of examination, the loss of data from the compression process is readily apparent.
Figure 6-8 Using the Camera Raw converter in Adobe Photoshop, you adjust bit depth, color space, white balance, image resolution and much more.
Figure 6-8A You can also correct a wide range of photographic issues and override the settings that were set on the camera when the picture was taken.
Figure 6-9 The History Log function can be enabled in Adobe Photoshop CS or later by choosing Edit from the Photoshop menu bar, then choosing Preferences and clicking in the options box to the left of the History Log option.
Figure 6-10A Using the digital camera’s default resolution of 72 PPI, the image, if printed, would measure 59.11 inches wide by 39.33 inches high. (You would need a large-scale printer to print a picture that large.)
Figure 6-10B By changing the image resolution to 300 PPI, the printed image would measure 14.187 inches wide by 9.44 inches high. (Again, you would need a large-scale printer to print a picture that large.)
Figure 6-10C By changing the image resolution to 900 PPI, the printed image would measure 4.729 inches wide by 3.147 inches high. (You could print a picture of this size on any printer.)
Figure 6-11 The conclusion from viewing the zoomed image is that there are five lines vertically and five lines horizontally in each of the numbered line sets.
Figure 6-12 The conclusion that would be derived from viewing the resampled image is that there are different numbers of lines of varying thicknesses vertically and horizontally in each of the numbered line sets.
Figure 6-13 Color laser printers use a series of cyan, magenta, yellow and black dots to represent pixel values. The white space between the dots is used to trick the eye into seeing different intensities (shades) of color.
Figure 6-14 Dye sublimation printers use the cyan, magenta, yellow and black dyes on the donor film to create color values that represent the pixel values. (If you look closely at this image, you can see the lines created by the heating process.)
Figure 6-15 The ridge detail in the digital image on the left is represented by a series of color dots as shown in the image on the right. If you compare the two images carefully, you can see that some of the minute detail in the digital image on the left does not appear in the printed image on the right.
Figure 6-16 While the image on the left does not appear to be affected by the use of a lossy compression capture format, the damage done to the image by the compression algorithm is clearly visible when the image is zoomed as shown in the image on the right.
Figure 6-17 While the image on the left illustrates the set of lines before the image was rotated and the image on the right shows the artifacts of the image rotate at 43 degrees.
Figure 6-18 Both images were enhanced using the exact same marquee selection box and the same settings and parameters. The image on the left illustrates the visual artifacts created when the selection is not feathered; the image on the right illustrates the when the selection is feathered and the enhancement blended into the rest of the image.
