If you are creating an image for on-screen viewing, you can decrease the number of colors to reduce the file size and ensure the image displays properly.
Before decreasing the color depth, consider the following:
If you are creating images for the Web, we recommend that you work with 16 million color (24-bit) images in the PspImage file format. After editing the images, you can reduce the color depth of the images and prepare them for the Web by exporting the images using the GIF optimizer, JPEG optimizer, or PNG Optimizer.
Depending on the current color depth of your image, you can decrease its color depth to the color depths described below.
2 colors (1-bit)
You can create a black-and-white image by decreasing the color depth of an image to 2 colors. For example, if your image is already black-and-white, you can change the color depth to two colors to reduce the file size.
16 Colors (4-Bit)
When you have an image that has only a few colors, you can decrease the color depth of an image to 16 colors (4-bit). This color depth is useful for simple graphics on Web pages that you want to load quickly. The resulting image has an image palette that contains 16 specific colors. You can change any of those colors by editing the image palette. For information, see Working with image palettes.
256 colors (8-Bit)
When you decrease the color depth of an image to 256 colors (8-bit), you can choose a Web-safe palette to ensure your image displays as expected regardless of the Web browser or monitor used to view the image. You can only convert color images to 256 Colors (8-bit). For information about converting images to 8-bit grayscale, see To create an 8-bit grayscale image.
Grayscale (8-bit)
You can convert a color image to an 8-bit grayscale image that uses up to 256 shades of gray.
32K and 64K Colors (24-Bit)
You can reduce the number of colors used in a 24-bit image by decreasing the color depth to 32K (32,000) or 64K (64,000) colors. Displaying images with 32K or 64K colors on older monitors results in better refresh rates than displaying 24-bit images with 16 million colors.
Decreasing color depth to a selected number of colors
You can decrease the number of colors used in an image by specifying the number of colors that you want to use. When you specify the number of colors, Corel PaintShop Pro converts the image to the appropriate color depth. For example, if you specify 16 or fewer colors, the image is saved as a 4-bit image. If you specify 17 to 256 colors, the image is saved as an 8-bit image. Specifying the number of colors is advantageous when saving to some file formats, such as GIF, because the file compression is sensitive to the number of colors in the image. For example, by using 100 colors instead of 256 colors, a smaller GIF file is created, even though both files are 8-bit images. Smaller files result in faster download times.
Edit workspace
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Choose Image  Decrease Color Depth 2 Color palette. |
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Choosing the Grey values option produces the best results in most cases. However, if the image consists mainly of a single color, selecting that color channel may produce the best results. |
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Weighted — weighted palettes produce less dithering and sharper edges |
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Non-weighted — non-weighted palettes produce more dithering and softer edges |
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Note: Dithering places pixels of different colors or gray levels next to each other to simulate missing colors or grays. |
You can also create a black-and-white image by choosing Adjust Brightness and Contrast Threshold. With this command, the color depth does not change. For more information, see To convert a photo’s pixels to black and white.
Edit workspace
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Choose Image Decrease Color Depth 16 Color palette. |
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Note: The Ordered Dither option is available only for the Windows color palette. |
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Boost marked colors by — when you have a selection in your image, this option lets you make the colors in the selection more important by a factor of the value you enter |
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Reduce color bleeding — makes the left-to-right bleed effect of colors less noticeable when you choose the Optimized Median Cut or the Optimized Octree palette and the Error Diffusion reduction method |
If you want to emphasize the importance of certain colors in the conversion, create a selection of the area that you want to use before you decrease the color depth.
Edit workspace
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Choose Image Decrease Color Depth 256 Color palette. |
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Note: The Ordered Dither option is available only for the Standard/Web-safe color palette. |
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Boost marked colors by — when you have a selection in your image, this option lets you make the colors in the selection more important by a factor of the value you enter |
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Include Windows’ colors — lets you include the 16 standard Windows colors in the converted image palette when you choose the Optimized Median Cut or the Optimized Octree palette option |
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Reduce color bleeding — makes the left-to-right bleed effect of colors less noticeable when you chose the Optimized Median Cut or the Optimized Octree palette and the Error Diffusion reduction method |
If you want to emphasize the importance of certain colors in the conversion, create a selection of the area that you want to use before you decrease the color depth.
Edit workspace
Edit workspace
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Choose Image Decrease Color Depth, and choose one of the following: |
Edit workspace
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Choose Image Decrease Color Depth X Colors (4/8-bit). |
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Boost marked colors by — when you have a selection in your image, this option lets you increase the colors in the selection by a factor of the value you enter |
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Include Windows’ colors — lets you include the 16 standard Windows colors in the converted image palette when you choose the Optimized Median Cut or the Optimized Octree palette |
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Reduce color bleeding — reduces the left-to-right bleed effect when you choose the Optimized Median Cut or the Optimized Octree palette and the Error Diffusion reduction method |
If you want to emphasize the importance of certain colors in the conversion, create a selection of the area that you want to use before you decrease the color depth.
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