Node: On EPS previews, Next: , Previous: The Emacs interface, Up: For advanced users



On EPS previews

preview-image-type
preview-image-creators
What happens when Dvips is finished depends on the configuration of preview-image-type. What to do for each of the various settings, what options to pass into GhostScript, and what Emacs image type to use is specified in preview-image-creators. The setting postscript is not offered when customizing preview-image-type since it is mostly of historic interest and will not work satisfactorily. preview-image-type defaults to png. For this to work, your version of GhostScript needs to support the png16m device. If you are experiencing problems here, you might want to reconfigure preview-image-creators or preview-image-type.

Most devices make preview-latex start up a single GhostScript process for the entire preview run (as opposed to one per image) and feed it either sections of a single PostScript file or separate EPS files in sequence for conversion into PNG format which can be displayed much faster by Emacs. Actually, not in sequence but backwards since you are most likely editing at the end of the document. And as an added convenience, any preview that happens to be on-screen is given higher priority so that preview-latex will first cater for the images that are displayed. There are various options customizable concerning aspects of that operation, see the customization group Preview Gs for this.

preview-gs-options
Most interesting to the user perhaps is the setting of this variable. It contains the default settings -dTextAlphaBits=4 and -dGraphicsAlphaBits=4. Decreasing those values to 2 or 1 might increase GhostScript's performance if you find it lacking.

Running and feeding GhostScript from preview-latex happens asynchronously again: you can resume editing while the images arrive. While those pretty pictures filling in the blanks on screen tend to make one marvel instead of work, rendering the non-displayed images afterwards will not take away your attention and will eventually guarantee that jumping around in the document will encounter only prerendered images.