ICO is  a well-known image format used for saving images that will be used for icons.  The format allows saving several different versions of the same image, at different sizes.  It does not provide coordinate system information.





Windows will usually preview the contents of .ico files as icons.


To import from ICO format:


  1. Choose File-Import from the main menu.

  2. In the Import dialog browse to the folder containing data of interest.

  3. Double-click the file ending in .ico for the data of interest.

  4. One or more tables and images will be created.




ICO files often contain multiple versions of the same image, saved in different sizes with different numbers of bits per pixel.  The names assigned to images that are imported from the ICO indicate the pixel size and depth.    For example, the Flower 001 48*48*8 image is 48 x 48 pixels in size and uses eight bits per pixel for colors, allowing 256 different colors.   The Flower 001 32*32*4 image is 32 x 32 pixels in size and uses only four bits per pixel, allowing only 16 colors.


We can double-click on images that are created to view them.   



The Flower 001 48*48*8 image appears above, with Zoom to Native used to show it in native, 48 x 48 pixel size.   It is not georegistered and has no coordinate system assigned.  By default, we can assign it a Pseudo Mercator projection, which is meaningless other than to provide a coordinate system for the pixels.




The Flower 001 48*48*4 image appears above.   It is the same size but uses only four bits per pixel for colors, so the 16 colors that are available produce a less lifelike image.     Modern computers have plenty of memory, but we still encounter collections of icons that use fewer bits per pixel to save space or which have persisted as a legacy from earlier days.




When importing an image to use as a bitmap symbol in Style, if the ICO file contains multiple images the Style dialog will not import them all. Instead, it only imports the image with the greatest size and the largest number of bits per pixel, that is, the most colors.  


For example, in the imported bitmap symbol created by importing from the Flower 001.ico file only the Flower 001 48*48*8 image was imported using the name Flower 001, and seen in use in the map above.


Using graphics files -  Images in formats such as BMP, PNG, ICO, etc.,  that do not provide coordinate system information can be handy as illustrations in layouts or for other purposes, such as sources for bitmap symbols in Style dialogs..    Manifold project files are so efficient that we can keep libraries of many images for fast viewing in Manifold, even if we do not intend to work with them in GIS.   We can also use Manifold to convert images between different formats, importing an image as one format and exporting it as another.


See Also



Style: Bitmap Symbols