If you must adjust the coordinates of a control point because the error is unacceptable, highlight the point in the Image Registration dialog box and choose another location for it in the Map window. To delete control points, click the point and choose the Delete button.
Raster Image Display Options
You can display more than one raster image in a window at a time. This is limited only by your computer's memory. However, if you want to digitize from the raster image, it is best to use only one image in a Map window. This is because two raster images will probably have slightly different rotations.
When using two raster images with different projections, keep in mind that MapInfo Pro will use the projection of the image that is opened first. This means that the second image is only positioned approximately.
Color (Raster Image)
Once you have displayed a raster image file in a Map window, you can make adjustments to the colors in the image. On the TABLE tab, in the Maintenance group, click Raster, and Adjust Image Styles to change the settings for that .TAB file. On the HOME tab, in the Windows group, click Tool Windows, and click Layers from the list, to open the Layers window, and then double-click on the layer name in the window to open the Layer Properties dialog box. On the Layer Display tab, select the Style Override check box and click the Style button to adjust the raster style only in this Map window.
The Adjust Image Styles dialog box lets you set the contrast and brightness of the image, set translucency, display color raster images in shades of gray, and make one color in the image transparent.
Using the Adjust Image Styles dialog box does not modify the raster image file; instead, it changes the way MapInfo Pro displays the raster image file. If you change an image's display style, MapInfo Pro records the new display style in the table file (for example PARCELS.TAB) or in the workspace for per layer styles, but MapInfo Pro does not alter the contents of the raster image file (PARCELS.GIF) in any way.
If you change an image's display style and choose OK, the new display style is applied immediately. It will also affect all Map windows in which the image is displayed if on the TABLE tab, in the Maintenance group, you click Raster , and Adjust Image Styles. You do not need to choose Save to save the changes.
Contrast and Brightness (Raster Image)
Adjusting a raster image's contrast and brightness can help make your map more readable. When you overlay additional map layers on top of your raster image, you may find it hard to tell which lines are part of the raster image and which lines are part of the additional layers. Changing the contrast and brightness can make it easier to differentiate the separate layers.
To soften the appearance of a raster image:
- On the TABLE tab, in the Maintenance group, click Raster, and Adjust Image Styles to open the Adjust Image Styles dialog box.
- Set the Contrast scroll bar to a low setting, such as 30%. (The default Contrast setting is 50%.)
- Set the Brightness scroll bar to a high setting, such as 70%. (The default Brightness setting is 50%.)
- Examine the image preview in the lower half of the dialog box. If the new display style suits your needs, choose OK. If you want to go back to the previous display style, choose Cancel.
Color to Gray-scale (Raster Image)
To change a color raster image to gray-scale, click the Grayscale button in the Conversions group of the Adjust Image Styles dialog box. To change it back, click the Original Image button.
Transparent Color (Raster Image)
You can also make one color in the image transparent. Making a color transparent will make the parts of the map displayed under that color visible. In the Adjust Image Styles dialog box, check the Transparent box to activate the Select Color button. Click Select Color. To select the color you want to be transparent, click the color in the preview image. The color you selected appears in a box next to the left of the Select Color button. The transparent color will display as white in the preview image. When you redisplay the image in the Map window, the selected color will be transparent.
Translucent Color (Raster Image)
MapInfo Pro provides the ability to display a translucent raster image. Translucent images allow you to partially see through them, enabling you to lay translucent raster images over other layers so that details of the layers below are partially visible. An image set to 0% translucency is completely opaque; an image set to 100% translucency is completely transparent.
Style Override for Raster Images
MapInfo Pro provides the ability to change the display style for raster and grid images on a per-layer basis through the Layers window. The Style Override option for raster images works the same way as it does for other map layers. In the Layers window select a raster layer in the list. Click the Layer Properties 
button. The Layer Properties dialog box displays. On the Layer Display tab, select the Style Override check box and click the Style button. The Adjust Image Styles dialog box displays. You can change any of the raster image style settings.
Zoom Layering for Raster Images
Zoom layering for raster images controlled from preferences (on the PRO tab, click Options, and Map Window, and then select Automatic Raster Zoom Layering). To change the zoom layering setting for a raster layer that you are currently working with, go to the Layer Properties dialog box (On the HOME tab, in the Windows group, click Tool Windows, and click Layers from the list, to open the Layers window, and then double-click on the layer name in the window) to either activate or turn off zoom layering. The setting is turned on by default.
Limitations in Using Raster Images
Many of MapInfo Pro's features cannot be applied to raster image tables. As a general rule, you cannot use MapInfo Pro to modify a raster image file. Specific limitations of raster tables include:
- No Data Saved with Raster Images: A raster table does not have columns, therefore, you cannot attach text or numeric data directly to a raster table, and you cannot perform queries, such as Find, on a raster table. You can, however, overlay a conventional (vector-based) MapInfo Pro table on top of the raster image, and attach data to the conventional table.
- Map Projections and Reprojections with Raster Images: When a raster image file displays in a Map window, the file that is opened first determines the projection of the map. If two raster images in a Map window use different map projections, MapInfo Pro will use the projection of the map that is opened first. The Map window will redraw slowly when you overlay other map layers on top of a raster image. The map redraws slowly because MapInfo Pro is re-calculating map coordinates so that the vector map objects conform to the projection of the raster image.