Thresholding is the ability of separating the picture elements (pixels) that make up an image in groups with similar characteristics.

Additional information about Color Thresholding is available from

Color vs. Monochrome Pixels These images illustrate the advantages that color thresholding offers over monochrome when trying to separate closely related hues. The blood cells in this capillary of the human liver stained with polychrome solution are easily distinguished from each other by their unique hues. Lymphocytes and nuclei are separated (arrows in 1-2) in color individually, but are grouped with other related hues in monochrome (arrows in 3-4). More details are found inPublications of this page.

Color vs. Monochrome Pixels The advantage of color over monochrome imaging is further illustrated in these figures. The arrow in Fig. 1 shows the a platelet (blueish) under an a red blood cell (yellow). There is no doubt about each hue and when thresholded (Fig. 2) only pixels of interest were turned on. Note the spread of chosen threshold value over closely related pixels and the difficulty locating the demarcation between the platelet and the red blood cell. More information about figures and publication source are found in New Items of this page.

Color vs. Monochrome Pixels This image represents portion of the nuclear chromatin of a hepatocyte magnified to show individual pixels. Those of closely related hues are grouped together. Note hues and saturation variability of pixel adjacent to those selected. Depending on the look-up table used for thresholding some of the pixels ignored with color could have been included in monochrome. Check Fermin et. al., J Anat 186:469-481, 1995.

		Differences between Monochrome & color spaces Objects of differing hues but of similar intensities will be viewed by a monochrome systems as closely related and thresholding is often difficult. In a color space separation is easier because the saturation of pixel color adds a third variable to separate differences between objects. For more details see Fermin & DeGraw J. Anat. 186:469-489, 1995 in Recent Publications.