Image Modes for Canvas X Paint Objects

In Canvas X Draw, image modes define the color model and number of colors that can be used in images. When you create a new paint object in Canvas X Draw, you select an image mode: Black & White, Grayscale, RGB Color, CMYK Color, or LAB Color. When you select a paint object, Canvas X Draw displays the image mode in the Properties bar.

The image mode also appears in the Status bar if Object Details has been selected to appear in an information field.

How Image Modes Affect Image Filters

Filters produce different results depending on the image mode. When you paint, the opacity setting of a brush acts differently on images in different modes. For the most predictable results with filters and paint tools, use RGB color mode.

Posterizing a LAB image introduces color to light areas.

How Canvas X Draw Assigns Image Modes

When you import an image from another source either by opening, placing, or pasting an image file, Canvas X Draw assigns an image mode based on the number of colors and the color model used in the image.

The following table shows the image modes that Canvas X Draw assigns when you import images in some common image formats.

Changing Image Modes

You might want to change modes so you can use certain features, or reduce memory requirements; e.g., you might want to convert an Indexed image to RGB to apply image filters. You might want to convert an RGB image to Grayscale mode to save memory when a document is printed without color.

You can access the Image Mode menu on the Properties bar or by choosing Image | Mode.

To Change Image Modes:

1. Select one or more paint objects.
2. Select the image mode from the Image Mode menu in the Properties bar.

Some modes are available only if the object’s current mode is compatible; e.g., Black & White mode and Duotone mode are available only when Grayscale paint objects are selected.

If the mode you choose does not support an image’s full color range, a message asks you to confirm the change. Click OK to proceed.

If you choose Duotone mode or Indexed mode, select options in a dialog box and then click OK to complete the conversion. (See Duotone Image Mode and Indexed Image Mode.)

Black and White Image Mode

Black & White image mode is used for scanned line art and black-and-white (“bitmap”) images, which contain only black and white pixels. Images in Black & White mode require the least amount of memory and disk space.

To Convert to Black and White Mode:

Grayscale mode images and Multichannel mode images are the only images you can directly convert to Black & White mode. If an image is not Grayscale, convert it to Grayscale mode first if you want to convert it to Black & White mode.

1. Select the paint objects and use the Image Mode menu on the Properties bar or choose Image | Mode | Black & White. The Select Halftone Method dialog box lets you choose a conversion option.
2. Select one of the following:
   • Pattern Dither: Canvas X Draw “screens” the image, rendering its tones as patterns of tiny dots, using a fixed pattern similar to a traditional halftone screen
   • Diffusion Dither: Canvas X Draw “screens” the image, rendering its tones as patterns of tiny dots, using a process that creates a random pattern effect.
   • Threshold: Canvas X Draw converts the image to a high-contrast, black-and-white image. Pixels of lightness values from 0 to 128 become black, and pixels of lightness values from 129 to 255 become white.
3. Click OK.

When you paste a selection into a Black & White image, Canvas X Draw uses diffusion dither on the selection.

Grayscale Image Mode

Grayscale mode is appropriate for images scanned from black & white photographs or when the image will never be printed in color. In Grayscale mode, pixels use 256 brightness levels to represent a range of shades from pure black to pure white. Grayscale uses 8 bits per pixel and requires less memory than most color modes.

If you convert a color image to Grayscale mode, Canvas X Draw discards all color information.

Indexed Image Mode

Indexed color mode uses a palette of 256 colors for images. Since this mode stores fewer colors, it requires significantly less memory than RGB and CMYK color modes, both of which support millions of colors. Smaller memory requirements make Indexed mode especially useful for images used on Web pages.

An Indexed image includes a color table, or palette, of colors used in the image. When you convert an existing image to Indexed mode, you can specify the number of colors from the image to include in the color table.

Most image filters, effects, and opacity controls aren’t available to be applied to Indexed images, except the Offset and De-Interlace filters.

To Convert an Existing Image to Indexed Mode:

1. Select the paint objects and choose Indexed from the Image Mode menu.

2. In the Indexed Color dialog box, choose an option in the Indexed Color dialog box for the color table.

   Depending on which method you select, the Colors area in the dialog box displays information about how the color table is computed.

Exact	Creates a color table from the colors in the image, if the image contains 256 colors or less; otherwise, this option isn’t available. The Colors area displays the number of colors in the selected image.
Uniform/ System	Creates a color table based on the operating system’s palette of 256 colors (System), or a subset of these colors (Uniform). The Colors area displays the number of colors in the operating system’s palette; if you choose Uniform, a pop-up menu that lets you select 8, 27, 64, 125, 216, or 256 colors appears.
Adaptive	Creates a color table from the most frequently used colors in the image. The Colors area displays a text box that lets you enter a number of colors from 2 to 256
Custom	Lets you create a color table, load, and save color table files. The Colors area displays “Custom colors”.
Previous	Applies the last color table used in the Indexed Color dialog box during the current Canvas X Draw session. The Colors area displays the number of colors in the last color table created by the Indexed Color dialog box during the current Canvas X Draw session.

3. Choose a color-distribution option in the Dither area:

None	Changes colors to their closest equivalent in the selected color table without dithering.
Pattern	Approximates colors not in the palette by arranging palette color in geometric patterns (available for Uniform/System method only).
Diffusion	Approximates non-palette colors by randomly dithering available colors; creates the most natural effect.

4. Click OK after choosing the settings you want.

If you select the Custom option, the Color Table dialog box appears.

To Create a Custom Color Table for Indexed Images:

1. Select “Custom” in the Indexed Color dialog box. (See Indexed Image Mode.)

If the image is already Indexed, choose Image | Mode | Color Table to open the Color Table dialog box.

2. Click OK.
3. In the Color Table dialog box, edit the settings.

You can edit individual colors in the palette, create a blend of colors, and select from several preset color palettes, including System and Grayscale palettes. In addition, palettes can be saved or loaded.

In the Color Table dialog box, a grid of 256 color swatches appears; each swatch represents one color in the palette. By default, the Custom option appears in the Table menu, and the color swatches show the last palette used in the dialog box.

The Table menu lets you choose among preset color tables:

You can also create a custom color table.

Saving and Loading Color Tables

By using the Load and Save options in the Color Table dialog box, you can save color tables to your hard disk or load a saved color table file into the Color Table dialog box.

To Load a Custom Color Table:

1. Click Load in the Color Table dialog box.
2. In the Load Settings dialog box, browse to the color table file you want to load, and then click Open. Canvas X Draw replaces the current palette in the Color Table dialog box with the new palette, and its name appears in the Table menu.

To Save a Custom Color Table:

1. Click Save in the Color Table dialog box.
2. In the Save Settings dialog box, enter a name for the table in the File name field. Before you type the file name, Canvas X Draw adds the extension .ACT in the field. Keep this extension when naming the file.

3. Specify a location on your hard disk to save the color table, and then click Save. Canvas X Draw saves the color table.

   Save your custom color tables in a central location on the corporate network and share them with co-workers.

To Customize Individual Colors:

After choosing a color table, you can customize individual colors in it using a color picker dialog box.

1. Click a color swatch to open a color picker dialog box.
2. In the color picker, select a color to replace the selected swatch in the palette, and then click OK.

To Customize a Color Table by Blending Colors:

Canvas X Draw lets you create blends of selected swatches in the color table. When you do this, the first and last swatches you select don’t affect the final blend in the color table. How the blend appears in the color table is determined by the two colors you choose in the Color Picker in step 2 of this procedure.

1. Drag across multiple color swatches to select them, (the more you select, the more gradual the blend will be). Selected color swatches appear highlighted with a black border, and then the color picker dialog box opens.

  

2. In the color picker, choose the first color, and then click OK. The color picker remains open; choose the second color, and then click OK. Canvas X Draw fills the selected color swatches in the Color Table dialog box with a ramp of the two colors.

RGB Color Image Mode

RGB color mode is used most often when working with high-quality full-color images, such as those from color scanners and digitized photographs stored on CD-ROM.

RGB color mode is the most reliable mode to use for images you want to modify with painting tools and filters. However, the full range of RGB colors exceeds the range that commercial printing can reproduce, so you should be aware of the limitations of the printing method that will be used. Also, an RGB color image is device dependent, which means that the same RGB values can look different when displayed on different monitors.

In RGB color mode, each pixel has a red, green, and blue component. Each component, referred to as a color channel, has 256 intensity levels. The combination of the intensity value in each channel creates each pixel’s color.

Remember that RGB is used for images on the Web and CMYK is used for print.

CMYK Color Image Mode

CMYK color mode is based on the four color inks used in commercial printing (and by some desktop printers): cyan, magenta, yellow, and black. Some color scanners can produce CMYK images.

In a CMYK color image, each pixel has a cyan, magenta, yellow, and black component. Each of these color channels has 256 intensity levels. The combination of the intensity value in each channel creates each pixel’s color. Because monitors are RGB devices, they can’t display CMYK colors directly. However, Canvas X Draw attempts to display CMYK images as they will appear when printed.

LAB Color Image Mode

The Commission Internationale d’Eclairage (CIE) developed the LAB color mode as an international color standard to overcome the device dependency of the RGB and CMYK modes. In a LAB color mode image in Canvas X Draw, each pixel has one lightness and two color components. The Lightness (L) channel has 256 levels of intensity. The two color channels, labeled A and B, provide a color range from red to green and yellow to blue, respectively.

Some companies sell collections of images in LAB color mode. Editing LAB color mode images with some filters or painting tools can have interesting and unpredictable effects.

Duotone Image Mode

In traditional graphics arts reproduction, a “duotone” is a grayscale image printed with black and an additional color. Canvas X Draw lets you create duotone images, as well as “monotone,” “tritone,” and “quadtone” images (printed with one, three, or four colors, respectively).

The term “Duotone” refers to the Duotone image mode, not just to images printed with two inks. In Duotone mode, an image can be printed as a monotone, duotone, tritone, or quadtone.

Printing images as duotones can add interest and increase the tonal range reproduced from grayscale photographs, without the additional expense of printing full-color images. The duotone effect can be subtle or striking, depending on the color used and the amount added to the image. In any case, the additional colors are used to reproduce the gray values in the image, rather than to reproduce specific colors.

To create a monotone, duotone, tritone, or quadtone in Canvas X Draw, you must convert a Grayscale image to Duotone mode. Unlike other image modes, once an image is converted to Duotone mode, you cannot work with individual image channels. Instead, you can adjust curves for each color “channel” in the Duotone Options dialog box.

To Create a Duotone Image:

1. Select paint object and choose Grayscale from the Image Mode menu to convert to Grayscale mode.

You can also select image modes by choosing Image | Mode.

2. Click OK when Canvas X Draw prompts to discard color information. Then, choose Duotone from the Image Mode menu.
3. Choose Monotone, Duotone, Tritone, or Quadtone from the Type menu in the Duotone Options dialog box. Depending on the Type setting, the Ink 1, Ink 2, Ink 3, and Ink 4 Curve boxes, color menus, and text boxes become available.

If you plan to export a duotone image to another graphics or page layout program, be sure the color names exactly match the color names in the other application. Otherwise, you might produce more color separations than necessary.

4. Choose ink colors by clicking the color palette icons and selecting colors in the palettes. You must have already added the desired colors to the Presets palette for them to be available in the pop-up palette.
   • For a monotone image, choose a single color in the Ink 1 area. For a traditional duotone, leave “Process Black” as Ink 1, and choose a second color in the Ink 2 area. For tritones and quadtones, choose additional colors for Ink 3 and Ink 4.
   • Canvas X Draw puts the name of the selected ink in the text box.
   • To use process colors: Type the appropriate name (“Process Cyan,” “Process Black,” “Process Magenta,” or “Process Yellow,”) so colors appear on the correct plates. If you leave the text box blank, Canvas X Draw prompts you to enter a name for the ink.
   • Specify ink colors in descending order of lightness value; i.e., darker color inks should appear at the top, and lighter color inks should appear at the bottom of the dialog box.
   • Assign only solid spot colors or individual process colors for duotones. If you assign a color ink made from CMYK components, Canvas X Draw treats it like a spot color and prints only one plate for the color when you output color separations.
5. If necessary, click the curve boxes to adjust curves for each ink color. In the Duotone Curves dialog box, drag the curve to adjust it, or enter values in the text boxes to map input values to the desired output values, and then click OK.
6. Click OK to apply the Duotone Options dialog box settings.

Duotone Options

You can select and change the following ink settings for images in Duotone mode.

To Adjust Duotone Images:

After you convert an image to Duotone mode, reopen the Duotone Options dialog box to adjust the color curves, change ink colors, as well as use the Load and Save options.

To Change Duotone Options:

1. Select the paint object you want to adjust and choose Image | Mode | Duotone Inks.
2. Adjust the settings in the Duotone Options dialog box and click OK to implement the new settings.

To Load and Save Duotone Information:

Use the Load and Save buttons in the Duotone Options dialog box to work with files of duotone options information. Canvas X Draw uses a file format compatible with the duotone options files used by the Photoshop image-editing program, so you can load files saved from Photoshop, and files saved by Canvas X Draw can be loaded into Photoshop.

1. Click Save to save the duotone options settings. In the directory dialog box, type a file name and click OK or Save.
2. Click Load to use settings from a saved duotone options file. In the directory dialog box, select a duotone options file and click Open. Canvas X Draw will apply the ink and curve settings saved in the file to the Duotone Options dialog box.

Multichannel Image Mode

Multichannel image mode lets you work with multiple channels of grayscale information for a grayscale image. In multichannel mode, each channel contains lightness values as in other image modes, but the values do not relate to color components.

When you convert an image to Multichannel mode, the image data does not change; e.g., if you convert an RGB Color mode image to Multichannel mode, the Red, Green, and Blue channels retain the same pixel information, but the channels no longer represent color pixels. The channels in Multichannel mode are labeled numerically (#1, #2, and so on) in the Channels palette.

The Multichannel mode is not available if you select a paint object containing an image in Black & White image mode.