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ImageViewer Intro
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Topics
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Rotate & Flip
Crop To Selection
Scale
Invert
Depth
Resolution
Brightness/Contrast
Sharpness
Special Commands For GIFs
Color Tables
Rotate & Flip
These operations require additional memory and may not execute if memory is low.
Rotate Left: Rotates the entire image counter clockwise 90 degrees.
Rotate Right: Rotates the entire image clockwise 90 degrees.
Flip Horizontal: Flips the entire image horizontally (i.e the pixels to left of center are swapped with their counterparts to the right of center).
Flip Vertical: Flips the entire image vertically (i.e the pixels above center are swapped with their counterparts below center).
To Rotate or Flip choose the appropriate command from the Modify menu.
Hint: To "mirror" half of the image, hold down the Shift or Option keys when flipping (not very practical but lots of fun!).
Limitations: Arbitrary rotation degrees, currently not supported.
Crop To Selection
Discards the portion of the image that isn't selected. The resulting image is a subset of the original.
To Crop To Selection choose Crop To Selection from the Modify menu.
Scale
Scales the actual image pixels. The original image size before the scale is always 100%. The image display mode is unchanged.
To Scale choose Scale from the Modify menu.
Invert
Inverts each pixel in the image.
To Invert choose Invert from the Modify menu.
Color Depth
Allows you to change the color depth or "bit level" of the image. This can be useful for reducing the image size, or matching the image to a display device depth. Optimize with Internet Colors, applies the standard color table used to display images on the internet(e.g. to display with web browsers). The internet color table has 216 valid entries.
To Set Color Depth choose Set Color Depth from the Modify menu.
Set Resolution
Allows you to change the resolution or dots-per-inch (dpi) of the image. Useful for reducing/enlarging the image size, or matching to a printer's resolution.
To Set Resolution choose Set Resolution from the Modify menu.
Brightness/Contrast
A dialog appears, which allows you to alter the brightness and contrast of the image. Moving the slider to the left reduces brightness or contrast, moving it to the right, increases brightness or contrast. If "Connect Colors" is checked the red, green, and blue channels are changed together. Turn this off, to adjust individual color channels.
To adjust Brightness/Contrast choose Brightness/Contrast from the Modify menu.
Limitations: Requires depth of at least 256 colors.
Sharpness
A dialog appears, which allows you to alter the sharpness of the image. Moving the slider to the left reduces sharpness(i.e. makes it duller or blurred), moving it to the right, increases sharpness. If Connect Colors is checked the red, green, and blue channels are changed together. Turn this off, to adjust individual color channels.
Radius, is how far the scan of pixels should go when determining the color environment surrounding a given pixel(usually 1 or 2 works well). Threshold, determines how different the brightness values must be between two pixels before it is included in sharpness equation.
To adjust Sharpness choose Sharpness from the Modify menu.
Limitations: Requires depth of at least Thousands of colors.
Special Commands For GIFs
Set Transparency, allows you to set the transparency for GIF files. An eyedropper icon will appear, clicking on the image will set the color. Remove Transparency, removes the transparency setting. You can also set transparency in the Save As dialog with the Options button. Currently, ImageViewer doesn't use transparency in its display, but saved files will retain this info.
Set Delay, allows you to set the delay time for multi-image GIF files(animated GIFs).
Choose the appropriate command from the Modify menu.
Color Tables
Apply Color Table, allows you to open a color table saved as a file, and apply it to the current image.
Save Color Table, allows you to save the contents of the current color table to a file, so it can be applied to another image.
To Apply or Save Color Table choose the appropriate command from the Modify menu.