Graphics |
8-Bit and 16-Bit Indexed Images
If the class of X
is uint8
or uint16,
its values are offset by 1 before being used as colormap indices. The value 0 points to the first row of the colormap, the value 1 points to the second row, and so on. The image
command automatically supplies the proper offset, so the display method is the same whether X
is double,
uint8,
or uint16
.
The colormap index offset for uint8
and uint16
data is intended to support standard graphics file formats, which typically store image data in indexed form with a 256-entry colormap. The offset allows you to manipulate and display images of this form in MATLAB using the more memory-efficient uint8
and uint16
arrays.
Because of the offset, you must add 1 to convert a uint8
or uint16
indexed image to double
. For example,
Conversely, subtract 1 to convert a double
indexed image to uint8
or uint16
.
Working with 8-Bit and 16-Bit Images | 8-Bit and 16-Bit Intensity Images |
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