Xara WEB File Export Dialog Box - Use JPEG on compatible bitmaps
When you export a document to a Xara WEB file all the 1 bit and 4 bit bitmaps in the document are automatically compressed using lossless compression. All 8 bit and 24 bit bitmaps are compressed using JPEG compression. JPEG is a more efficient way of compressing bitmaps of this type but it does discard some information in the process. This is generally not noticeable, especially when using high JPEG Quality settings. If you want to export your 8 and 24 bit bitmaps using lossless compression, deselect this option.
When you create a WEB file with this option selected, all the 8-bit and 24-bit bitmaps in the document not already in JPEG format are converted before they are saved in the file. The JPEG Quality slider controls the amount of compression. Low values give the greatest compression but the most information loss. If you set the value to the highest, the bitmaps do not compress so well, but are very high quality. The slider is dimmed if there are no bitmaps in the document that can be converted to JPEGs.
You can experiment to get the best setting for the bitmaps by creating several WEB files from the original XAR document using different JPEG Quality setting and loading them back into Xara LX. You can then compare the file size and the quality of the WEB file with the original XAR file. Remember that once you close the original XAR file, you retain only the JPEG compressed versions of the bitmaps in the WEB file.
Important: Once you have exported a WEB file with this option set, you cannot reload it and export it again at a different JPEG Quality setting as all the suitable bitmaps have been converted to JPEG bitmaps already. When you reexport a file like this all the JPEG bitmaps stay the same. Bitmaps are never recompressed using JPEG compression as this causes quality loss.
Tip
If you want to change the JPEG Quality for an individual bitmap, export it from Xara LX as a JPEG file. Vary the JPEG Quality in the bitmap export dialog box until you get the file size you want at the quality level you want. You can then re-import the bitmap and export the WEB file.