chapter  5
20 Pages

Image Analysis Operations

WithElizabeth Berry

This chapter examines the key arithmetical, logical and morphological image analysis operations. Familiar arithmetical operations, such as addition, subtraction and multiplication, can be performed on the pixel values of digital images. Common operations that involve one image and a numerical constant are add, subtract, multiply and divide. The data type is important because of the potential for the calculated value to lie outside the range of the original image data type. Run the cursor across the image from left to right, watching the display of pixel values shown at the bottom left of the ImageJ menu. Spatial calibration ensures that the real-life size is associated with each pixel of an image. In an uncalibrated image there is no guarantee that, in a pair of images from the same modality but acquired at different times, the same gray value is associated with the same object material. Morphological operations involve one image and a small binary template called a structuring element.