Decreasing the color depth of an image
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:
• Most Corel PaintShop Pro effect and correction commands work on 16 million-color and grayscale images only.
• When you decrease the color depth, Corel PaintShop Pro flattens the image, which merges the data on all layers. However, you can add vector layers to images of any color depth.
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.
To decrease the color depth to 2 colors
Edit workspace
1 Choose Image Decrease Color Depth 2 Color palette.
2 In the Palette Component group box, choose the color channel to use for the final image.
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.
3 In the Reduction Method group box, choose a color reduction method.
4 In the Palette Weight group box, select an option:
• Weighted — weighted palettes produce less dithering and sharper edges
• Non-weighted — non-weighted palettes produce more dithering and softer edges
Note: Dithering places pixels of different colors or gray levels next to each other to simulate missing colors or grays.
5 Click OK.
To decrease the color depth to 16 colors
Edit workspace
1 Choose Image Decrease Color Depth 16 Color palette.
2 In the Palette group box, choose a palette option.
3 In the Reduction Method group box, choose a color reduction method.
Note: The Ordered Dither option is available only for the Windows color palette.
4 In the Options group box, mark or unmark these check boxes:
• 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
• 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
5 Click OK.
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.
To decrease the color depth to 256 colors
Edit workspace
1 Choose Image Decrease Color Depth 256 Color palette.
2 In the Palette group box, choose a palette option. For more information about setting Palette options, see
Working with image palettes.
3 In the Reduction Method group box, choose a color reduction method.
Note: The Ordered Dither option is available only for the Standard/Web-safe color palette.
4 In the Options group box, choose any of the following options:
• 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
• 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
• 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
5 Click OK.
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.
To create an 8-bit grayscale image
Edit workspace
• Choose Image Greyscale.
To decrease the color depth to 32K or 64K colors
Edit workspace
1 Choose Image Decrease Color Depth, and choose one of the following:
• 32K Colors (8 bits/channel) — reduces the number of colors to 32,000
• 64K Colors (8 bits/channel) — reduces the number of colors to 64,000
2 In the Reduction Method group box, select a color reduction method.
3 Click OK.
To decrease the color depth to a selected number of colors
Edit workspace
1 Choose Image Decrease Color Depth X Colors (4/8-bit).
2 Type or set the number of colors (from 2 to 256) in the Number of colors control.
3 In the Palette group box, select the palette options.
4 In the Reduction Method group box, choose a color reduction method.
5 In the Options group box, choose any of the following options:
• 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
• 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
• 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
6 Click OK.
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.