7.1

749
Color Correction Editor
Histogram
The Histogram shows the distribution and frequency of the RGB values contained in an image. It has no
spatial relationship to the associated image.
Color correction using the Histogram (HistoMatch) is described elsewhere: page 762.
Histogram Display
 A field is displayed for each channel (red, green, blue).
 The values are plotted from left to right on the X axis (0 to 255), the scale is divided by 10 scale
marks along the upper horizontal lines.
 The two inner dotted red lines indicate the edges of the permissible range (approximately as per
CCIR 601) and the outer dotted lines represent 0 and 255. See “Legalizer” on page 751.
 The Y axis (from bottom to top) represents the number of pixels for each point along the X axis.
The Y axis is scaled so that the full height of the scale always represents the maximum value
detected, the others adapt accordingly.
 The histogram for a reference source is dark blue; wherever values overlap, the green histogram
of the current image is somewhat brighter.
For example, the histogram of a fully saturated red color clip (255,0,0) comprises a green vertical line at
position 255 in the R field and two lines at position 0 in the G and B fields. Clearly stated, all the pixels
contained in the image are red=255 and it contains no values for the other two components. The histo-
gram for a dark-green color clip (25,25,25) displays the three lines (full height) at the same X positions.