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While many of you astute readers probably know all about the various bitmap export file types, your editor will try to enlighten himself, and those of you not
familiar with these bitmap formats on this page.
NOTE:
If you want very detailed information about bitmap file formats, how the file processes the color information, compression methods and such, here are two links to sites that will explain it all in great detail:
CICA Graphics List Image File Formats
The Graphics File Formats Page
BMP (Windows Bitmap)
This is the native Windows bitmap file format, although there is also an IBM OS 2 version. I use this format for screen captures, without compression, as it produces clean, sharp images which can be reduced to 256 or 16 colors for the Web. (
JPEG images create too many blotchy areas). Uncompressed BMP
files also compress tremendously when Zipped making it a good file format for sending large images. Files can be saved in True Color (16.7 million colors), 256, 16, and 2 color depths.
DCX
Near as I can tell, this is a multiple page file format used for transmitting facsimile (FAX) images. I exported the owl image using the default settings and then imported it back into Xara and it looked just like the 16 color
GIF and PNG files.
GIF (CompuServe Graphic Interchange Format) This file format was created in the early days of the Web when modems were very slow (200 kb and less,
compared to 56K and higher speeds supported today). This file format is limited to 256 colors or less. The initial version did not support transparency, the current version (GIF 89a) supports one transparent
color and can be used to create images with transparent backgrounds. You can specify Optimized palette, which picks the best range of colors for your image, Browser, which picks colors from a palette
of 216 web safe, non-dithering colors, or Web Snap Optimized
which attempts to skew colors to their closest Web safe equivalents when practical and uses the optimized colors when a close match is not possible. Of the three options, the Browser
palette option generally produces the smallest file size at the expense of image quality. Because of the limited range of colors in the Browser palette, it may be necessary to use Error Diffusion
dithering. On the other hand, if you have an image with mostly solid colors, and have selected your colors from the Web Safe Colors (the diamond shaped colors on the screen palette) then the Browser option is the one to use.
JPG (JPEG Joint Photographers Expert Group). This file format was developed as a way to greatly compress large bitmap images making it easier to
transmit the file over the Internet, download into Web Browsers, and to store on removable media or hard discs. Another important consideration when developing this file format standard was interchangeability
between various platforms and software applications. While JPEG images do not currently support Alpha channel transparency, a new standard currently being developed will very soon. Although JPEG
images may be highly compressed with some visible image degradation, you can also save images with no compression and retain all of the image quality. JPEG images use what is known as Lossy
compression. This compression method discards information for pixels that are not visible.
PCT (Macintosh PICT) A file format common to the Macintosh platform and used in graphics, and page layout applications, and Quick Time movies for
transferring images between platforms. This file format can greatly compress images containing large areas of flat color or Alpha channel transparency. Xara's PCT
export filter allows for color depths of True Color, 256, 16, and 2 colors. You can also specify Browser or Optimized palette and Error Diffusion
dithering for all color depths except True Color. (At 16.7 million colors, True Color does not need dithering)
PCX PaintBrush
An older file format developed by Zsoft for PC Paintbrush (now Corel Photo-Paint) for use on the IBM PC computer platform. I'm not real sure why anybody would use this file format when there are many newer and more versatile formats. You can export files with the same options as the
PCT
format. You cannot directly specify the resolution, but you can modify the dimensions which will in effect alter the dpi resolution. I exported the owl image at twice the size an imported the image back into Xara. The image was twice the size (as one would expect) and very sharp and clean. This indicates that Xara used the hidden pixel information in the owl image (it had been reduced to about 25% of its original size for these examples) in creating the larger image. I suspect this is true of all images exported from Xara where the original image was larger than the image being exported.
PNG (pronounced PING) Portable Network Graphic
is a new file format that can produce a range of bitmaps from two colors to 32-bit with Alpha channel transparency. Bitmap images created in Xara with the Create Bitmap Copy command are PNG images.
RAS (Sun Microsystems Rasterfile) The native file format for Sun Microsystems computer systems. The same export options are available as for most
file exports. My guess is you could use this file format to create images for Sun's various computers, but then you could probably use any of these file formats on this page as well.
TGA (Targa) This file format was developed by AT&T for their TrueVision software. I do not know of any reason to use this file format unless it
is specifically requested. I use a stereogram application, PopOut Pro that can only work with 16 color BMP or 24-bit TGA images. I use the TGA
option. All the export options exist for this format. CorelDRAW offers a Compressed option that Xara does not, but as PopOut Pro can only work with non-compressed images it makes no difference.
TIF (TIFF Tag Image File Format) For my money (and most people's as well) this is the only file format for creating bitmap images for commercial
printing. Created by Microsoft, Aldus and NeXT this is also the choice of many people when scanning images. As with many file formats, TIFF
was designed to be exchanged across platforms and used in most software applications. Many revisions to the TIFF file standards have been made. Xara TIF
export filter permits you to select from a selection of resolutions or you can enter your own resolution. You can also select from LZW (Lempel-Ziv Welch compression algorithm) compression or no compression.
You can export TIFF files in compressed format in True Color and 256 colors. No compression is available for 4-bit (16 color) images. When exporting 1-bit
TIFF
images (black and white) you can choose from Huffman, Group 3 and Group 4 FAX and Packbits. All of these 1-bit formats are probably best for creating a Facsimile (FAX) image and all look pretty much the same when imported into Xara.
I created a 600 dpi TIFF image of the owl with and without LZW
compression. The difference was about a 3-1 compression. The non-compressed version was 9.5 MB while the LZW compressed version was 3.75 MB. A fair savings. While the compression is not as spectacular as
JPEG, TIFF files loose very little information when compressed and decompressed.
Xara can only export RGB TIFF
images. Most commercial printers prefer the image to be in CMYK. If you have access to Photoshop, or any other bitmap editing application, you can import the TIFF
image and change the mode to CMYK. Or you can visit the XaraXone Shareware page and download Sean Sedwards' XPort CMYK plug-in filter (6 K), which lets you convert your images to CMYK right in Xara. Either Create a True Color
Bitmap Copy of your image in Xara, or import a TIFF file, then select XPort CMYK from the Plug-ins menu and take it from there. There is a ReadMe file in the Zipped download file.
NOTE: Commercial printers use the measurement LPI
(Lines Per Inch) to specify image resolution. This is different from Xara's (and most graphics applications DPI or PPI
(Dots or Pixels Per Inch). To export your image for commercial printing, double the DPI amount of the requested LPI setting. For example, if your commercial printer is printing at 300 LPI, high
quality printing, you would export your image at 600 DPI.
TIP:
Xara imports most bitmap images at a 1:1 basis. Thus an 200 dpi image will import twice as large as the same image exported at 100 dpi. This is not true with TIFF
images. They generally import at the same size they were exported. So when I exported by owl image at 600 dpi at a width of 250 pixels, it imported at the same 250 pixel width and looked like a dog's breakfast (not very pretty). If you select the image, then go to
Utilities > Bitmap Effects and Plug-ins... > Bitmap Effects... > Resize, see what the actual width is in pixels, then enter the width on the Width
text entry box on the Infobar, you will see the TIFF image at actual 1:1 resolution and everything will be sharper and clearer.
WPG (Corel WordPerfect Group) This file format is the preferred file format for use with Corel WordPerfect. The export settings support 8, 4, and 1
bit color depths and has no compression options. Palette options include Optimized and Browser.
And that wraps up your editor's limited knowledge of Xara's Export filters and settings. If I made any really glaring errors, I'm sure you will be good enough to
let me know, eh?
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