Sigma DP1 user manual Histogram

HISTOGRAM

The histogram is a graph depicting the distribution of brightness values in the image for each of the three color channels (Red, Green, and Blue). The horizontal axis shows the brightness level, with darker pixels towards the left side and brighter pixels toward the right. The vertical axis shows the proportion of pixels at each level of brightness.

By examining the histogram of the full image, you can gauge the overall exposure of that image. You can also use the histogram to determine if zoomed-in sections of an image are over or under exposed.

This histogram shows that the higher pixel values are never used in the image, indicating that the image is underexposed, and therefore will appear dark. In general, when the histogram is higher on the left side, the image is mostly composed of dark pixels, causing it to appear dark—either because the image is underexposed or because it is a dark scene such as night shot or sunset.

This histogram shows a fairly even distribution of pixel values, indicating that the image is well exposed, with good contrast. However, the histogram distribution of a well exposed image will vary greatly depending on the subject.

This histogram shows that many of the pixel values are at their brightness limit, indicating that some areas of the image may be blown out. In general, when the histogram runs off the right side, the image will have many white pixels—either because the image is overexposed or because it is a bright scene such as the beach or snow.

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