Computer imaging concepts 3.

Color management of graphics.

Color management in the use of
    -input devices such as scanners, digital cameras and digital x-rays
    -output devices such as  printers and monitors.  

Know:
    -the resolution (number of pixels on a screen)
    -size (height and width of image)
    -bit depth (number of colors in each pixel) of the image coming from the input device.

-dental digital x-rays have an 8-16 bit depth --gray scale.  
-an intra-oral (wand) camera usually has 24 bit RGB image.
-a scanner has a variety of settings as determined when scanning.
                -Best to set physical properties initially.
                -It can also be edited, after acquired, within a graphics program.

For output to a printer use the 24 bit setting to print to a RGB (red, green, blue) or a CMYK (32 bit)  printer.

 

You can convert a 24 bit color image to grayscale (8 bit, 256 shades) and decrease the file size.

You may also convert a 24 bit image to a smaller file size, 256 colors--8 bit image. This results in a loss of some color intensity.    For such conversions CorelPaint™ and Photoshop (Elements)™   can be used. This example is taken from CorelPaint™ and shows the conversion of a 24 bit image to 8 bit, 256 color image.  If it is done without a process called dithering, poorer results are obtained.

Dithering is created by averaging the depth of adjacent  pixels when pixels (resolution) are  up-scaled or down-scaled to create a homogeneous appearance of colors or shades of gray. Image Dithering is a method of enhancing the appearance of photographic images when the original color palette is changed. With dithering that is ordered or using error diffusion, a better result is observed. (Ref: Mohler JL, Grpahics, Animation and Multimedia, pp 103-142, Sams.net Publishing, Indianapolis, 1997.)

Page One     Previous     Next