Frame editing: Special functions: Raster graphics frames (en)

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Frame editing > Special functions Index

Special functions: Raster graphics frames

This function group will appear if you click on the question mark icon in the Frame editing function group while the icon for raster graphics frames is selected. The raster graphics frame icon will automatically be selected when a frame of that type is active.

This function group contains all the functions designed for working with raster graphics. For more information on raster graphics, see the chapter Fundamentals, Vector and raster graphics. You can also modify colour images here. For greyscale and colour images you can set the control curve for the raster transformation, and you can use various functions to control the size of any raster graphic. Finally, there are functions that allow you to crop (delete part of) an image or add a surrounding margin to it.

You will also find here functions for converting the colour depth of raster graphics frames. Please note that converting an image to a colour space with a lower colour depth (say RGB-colour to grey) may basically lead to a loss of colour information.

Beside the usual colour spaces CMYK, RGB, greyscale and monochrome you can also convert your raster graphics to palette images (duochrome or 256 colour) here. Furthermore Calamus lets you colourize greyscale images (also with real spot colours) and create duplex, triplex and quadruplex images here.

When a graphic frame is selected, the icons will show the current colour space of the image. This allows you to find out easily, for instance, whether the image has already been separated into CMYK or is still present in RGB format.

If you have selected a raster graphics frame and click on one of these icons, the following dialog appears:

Here you can set the desired target (resultant) resolution. A click on the Original resolution button sets the present image resolution, and a click on the unit of measurement following the resolution value switches between dpi and pixels. When converting colour or greyscale images to monochrome ones, you can also specify how the colour and grey values are to be converted to monochrome. Rasterize means that the image will be rasterized with the raster that is currently selected in the Raster generator for this frame. As usual the hierarchic principle applies here too: If no raster is set for the frame then that for the page will be used; if there is none for this either, then that of the document. If Dither is selected then the Ordered dither process will be used. When converting greyscale images to monochrome, then instead of rasterizing you can set a Threshold value. A threshold value of 50 % for instance will result in all parts of the image that have a grey value lighter than 50 % becoming white while all darker ones become black.