Corel Painter Help | Choosing a file format

Choosing a file format

When you save a file, you must choose a file format. The following section contains information about some of the supported file formats.

Saving RIFF files

RIFF is the Corel Painter file format, which retains special information about your document. For example, a RIFF file maintains all layers.

RIFF files are best used as "work-in-progress" files. It is recommended that you always save files in RIFF format, and then save to GIF, JPEG, TIF, or another file format when a file is ready for production.

Corel Painter lets you compress files and save disk space with a lossless compression method. When saving in RIFF format, you can minimize the file size on your hard disk by ensuring that the Uncompressed option is disabled by default.

Saving JPEG files

Corel Painter supports the JPEG file format. Unlike GIF, the JPEG file format displays a full range of colors.

The JPEG file format lets you compress your file on a scale of Fair to Excellent, where quality is directly proportional to file size. These quality settings will let you achieve compression ratios ranging from less than 10:1 to greater than 100:1. JPEG is a "lossy" file format, meaning that a compressed JPEG file will not be identical, pixel-for-pixel, to the original. However, because the JPEG algorithm takes into account the sensitivity of the eye to different colors, the higher-quality settings should achieve visually satisfying results.

You can assign a URL to layers and placed images and then save the file in GIF or JPEG format to produce an image map. For more information, see Creating image maps.

When you save a file in JPEG format, Corel Painter displays the JPEG Encoding Quality dialog box, with the following options:

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The Quality options — Excellent, High, Good, and Fair — let you set the degree of file compression.

The Excellent option compresses the least, but retains the most data. Fair compresses the most, but loses the most data.

You can also use the Quality slider to adjust file compression.

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The Smoothness slider applies smoothing to the entire image. This is useful when using the Fair option to blur the edges of JPEG artifacts. The default is 0. Keep in mind that using a high smoothness setting can cause blurring.

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The Progressive JPEG check box creates a progressive JPEG file. The progressive format is useful for files designed for the Web. As the name implies, the progressive format displays an image in stages — as a series of scans — while the file downloads. The first scan is a low-quality image; the following scans improve in quality. This allows the user to see the whole image quickly.

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The HTML Map Options — NCSA Map File, CERN Map File, and Client Side Map File — let you generate an image map. (NCSA refers to the National Center for Supercomputing Applications, and CERN refers to the Conseil Europeén pour la Recherche Nucléaire.) Use the NCSA Map File or CERN Map File option to generate a server-side image map. Use the Client Side Map File option to generate a client-side image map.

For more information, see Creating image maps.

It is best not to decompress and recompress a file multiple times. Although JPEG can compress and discard data that is not visible or obvious, the degradation of the data can affect the condition of your file.

When a file has lost a significant amount of data, block patterns may appear in areas of the image. If you try to use the Apply Surface Texture feature on a JPEG file, you may find that the block patterns become more prominent.

Saving GIF files

Corel Painter lets you save documents as GIF files. GIF, a file format using 8 or fewer bits, is commonly used to display graphics on the Web. When you save a GIF file, you can choose settings from 4 Colors to 256 Colors. You can choose how your colors will be displayed and what part of your image will be transparent.

You can enable the Color Set option to force all colors in the color table of the GIF file to match the colors in the current color set. This option can be useful when you are doing Web work, especially if you want to constrain colors to a specific color set or control the number of colors on a Web page, thus controlling the image file size.

The Imaging Method setting determines how a 24-bit Corel Painter document will be converted to the limited number of colors that GIF uses. If you choose Quantize to Nearest Color, Corel Painter may replace some colors with colors that are located next to each pixel. If you choose Dither Colors, Corel Painter applies a pattern to the chosen colors to generate a more accurate, less banded result.

Corel Painter can also save a frame stack as a GIF animation file. For more information, see Exporting animated GIFs.

If you want your image to have transparency, enable the Output Transparency check box. Most programs that display GIF files support transparency, but for those that don’t, you should specify the color of the "transparent" area. If your image will be displayed on the Web, enable the Background is WWW Gray option. You can also choose to use the background color of your Web page by enabling the Background is BG Color option.

For programs that support transparency, your selection will determine which areas are transparent. The Threshold slider determines which selection (loaded mask) value becomes transparent. You can see how the Threshold slider affects the transparency of your image in the Preview window of the dialog box. Transparency is displayed in the Preview window by a rectangular lattice. You can toggle between the Preview window and your Save As GIF options to the results you want. Enable the Interlaced check box if your image will be displayed on a Web page.

For more information, see Selections and transformations.

Saving RGB TIF files

The TIF format facilitates exchange between applications and computer platforms. It is a widely supported bitmap image format that lets you save RGB color profile information.

Saving Adobe Photoshop (PSD) files

Corel Painter can save files in Adobe Photoshop (PSD) format. For optimum compatibility, shapes and text are rasterized, and masks are placed in channels.

When you save a file in PSD format, you can embed the RGB color profile, as you do when saving in TIF format.

Saving Encapsulated PostScript (EPS) files

The encapsulated PostScript (EPS) files in Corel Painter conform to the Desktop Color Separation (DCS) 2.0 format (EPS-DCS 5 file format). Although Corel Painter saves files in EPS-DCS, it can’t read EPS-DCS. If you plan to save an image in EPS-DCS, it’s a good idea to save it in another format first, so that you’ll have a copy of it that you can reopen in Corel Painter.

When you save an image as an EPS-DCS file with Preview Options turned on, Corel Painter uses the loaded International Color Consortium (ICC) profile to prepare the separation files. For more information, see Printing images.

Although you can save your images as CMYK EPS separations, Corel Painter can’t open or edit CMYK files.

When you save a file in EPS-DCS, Corel Painter opens the EPS Save Options dialog box, with these options:

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Hex (ASCII) Picture Data provides another way of storing PostScript information. Some page design programs require that this option be checked. The file sizes will be approximately twice as large when saved with this option.

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Preview options — No Preview, Black and White Preview, and Color Preview — specify whether to save preview data and in what format. The resulting preview file is a low-resolution (72-ppi) file.

If you have an older laser printer, you must use the black and white preview to print these files. Although the preview or display is black and white, the color information remains intact.

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