| # Medium selection and definition

Index XSane mode: Viewer mode Save mode Copy mode Multipage mode Fax mode E-mail mode Gimp plugin Scan options Medium selection Color management Color correction: Gamma correction Brightness Contrast Threshold RGB default Negative Autoenhancement Default Restore Store Histogram window Pipette functions Standard options window Advanced options window Preview: Pipette white Pipette gray Pipette black Unzoom Zoom out Zoom in Undo zoom Autoselect scanarea Autoraise scanarea Select visible area Delete preview cache Preset area Rotation Aspect ratio RGB values Select scanarea Move scanarea Batch scan: Empty batch list Open batch list Save batch list Add area to list Remove selection Rename selection Rotate image Mirror image Setup: Copy setup Display setup Enhancement setup Fax setup Filetype setup E-mail setup Saving setup Color management setup | Medium selection: Select the medium from which you want to acquire an image. For reflective scans (photos, magazines, etc.) select full color range. XSane comes with some predefined media. With some luck you can use such a predefined media, but in general you have to create your own media definitions because each scanner model generates slightly different colors. Especially for negatives you have to define a media for each negative type because they all have a different color of the film mask. When you change the selection then it may be necessary to do a new preview scan to get correct colors in the preview window. The small point left of the Acquire Preview button in the preview window tells you if the preview is correct or not. Set the color correction sliders to default before you do a preview scan. With a correct media definition you should get a preview with more or less natural colors. But you have to apply a color correction afterwards. You can not expect that the results are ok without a fine correction of the colors. You can start with an automatic correction but especially for negatives it is good to do a manual fine correction before the final scan. Create or edit a medium definition: You can create and store your own definitions for different source media. In the preferences menu there is an item edit medium definition. When you enable this item then the icon before the slection menu of the medium gets a little slider on its right side: Edit medium definition: When this icon is visible then you can edit and create medium definitions. Do not use this mode to scan images, xsane will not behave like you expect when you try to scan images in this mode. To define a medium for color scan disable the RGB default button then you have sliders for each color separately. When you want to define a medium definition for a negative then activate the negative button. Now do some preview scans from the medium you like to define. Set the color correction sliders brightness and contrast so that you cut almost all unused color levels. Do not cut any used color levels. It is better to keep a little safety distance to the used colors. You can do a color correction later in the preview window to cut unused colors, but when your medium definition cuts colors that are used in your images then you are not able to get these colors back. For negatives it is a good idea to select a part of the frame around the image, but if possible do not select any holes. The frame around the image defines the color of the film mask. In general the image does not contain such a color but you can be sure that this mask defines one end of the used color range. Set the gamma sliders so that you get natural colors. If you are unsure better leave the gamma value close to 1.0, you can apply the gamma correction later. To save the new definition or to rename, delete or reorder existing definitions: open the medium menu with a short click with the left mouse button. Move the mouse pointer to the entry that you want to edit or where you want to add the new entry. Press and hold the right mouse button to open the context menu. Select a function in the context menu: Remark: The item add medium definition is only available in the context menu when edit medium definition in the preferneces menu is enabled. When you save new media definitions then please use the manufacturer and the type of the medium as name. Disable edit medium definition in the preferences menu. Test the newly created medium definition. It may be necessary to repeat these steps some times for fine correction to get a usable definition. When you created good medium definitions please send the file ~/.sane/xsane/xsane.mdf to Oliver Rauch and please tell me the name of the scanner that was used to create the medium definitions. I hope we can generate a database of medium definitions for different scanners.

> Author: Oliver Rauch