Networking
Bit depth/image size
A pixel is the smallest element of a digitized picture. A smaller pixel size will generally give an improved spatial resolution in the image. The pixel pitch is the distance between the centres of adjacent pixels.
The matrix size is the number of pixels or memory locations into which the image is divided. Thus, the total number of pixels in a 1024 x 1024 matrix is 1 048 576, defined as one megapixel.
The bit depth of the image determines the contrast resolution. The analogue value of the output from each pixel is converted to digital form, and the results are stored at a separate location in a matrix. The number of grey levels available equals two to the power of the number of bits, e.g. 28 = 256.
Clinical images require good contrast resolution, which is difficult to achieve due to the noise inherent in a radiographic image. In order to achieve good contrast resolution, high bit depths are required. The number of bits required depends on the noise
level: the lower the level of noise, the higher the number of bits that can be used.