Adobe photoshop cs2 Benutzerhandbuch
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ADOBE PHOTOSHOP CS2
User Guide
to surrounding pixels and diffused throughout the image, resulting in a grainy, filmlike texture. This option is useful
for viewing images on a black-and-white screen.
for viewing images on a black-and-white screen.
Halftone Screen
Simulates the appearance of halftone dots in the converted image.
Custom Pattern
Simulates the appearance of a custom halftone screen in the converted image.
Original grayscale image, and 50% Threshold conversion method
Pattern Dither conversion method, and Diffusion Dither conversion method
To convert a Bitmap mode image to Grayscale mode
You can convert a Bitmap mode image to Grayscale mode in order to edit it. Keep in mind that a Bitmap mode image
edited in Grayscale mode may not look the same when you convert it back to Bitmap mode. For example, suppose a
pixel that is black in Bitmap mode is edited to a shade of gray in Grayscale mode. When the image is converted back
to Bitmap mode, that pixel is rendered as white if its gray value is above the middle gray value of 128.
edited in Grayscale mode may not look the same when you convert it back to Bitmap mode. For example, suppose a
pixel that is black in Bitmap mode is edited to a shade of gray in Grayscale mode. When the image is converted back
to Bitmap mode, that pixel is rendered as white if its gray value is above the middle gray value of 128.
1
Choose Image > Mode > Grayscale.
2
Enter a value between 1 and 16 for the size ratio.
The size ratio is the factor for scaling down the image. For example, to reduce a grayscale image by 50%, enter 2 for
the size ratio. If you enter a number greater than 1, the program averages multiple pixels in the Bitmap mode image
to produce a single pixel in the grayscale image. This process lets you generate multiple shades of gray from an image
scanned on a 1-bit scanner.
the size ratio. If you enter a number greater than 1, the program averages multiple pixels in the Bitmap mode image
to produce a single pixel in the grayscale image. This process lets you generate multiple shades of gray from an image
scanned on a 1-bit scanner.
Specifying the halftone screen for Bitmap mode images
The Halftone Screen option in the Bitmap dialog box lets you convert a grayscale image to simulated halftone dots.
Important: The halftone screen becomes part of the image. If you print the image on a halftone printer, the printer will
use its own halftone screen as well as the halftone screen that is part of the image. On some printers, the result is a moiré
pattern.
use its own halftone screen as well as the halftone screen that is part of the image. On some printers, the result is a moiré
pattern.