Notes from the Manual: Histograms Part IV

Understanding Histograms: Part IV

Excerpt from the Canon Boot Camp Manual

Blown out whites Whites and Grey Whites

We’ve zoomed into the nun’s cowl by her temple. (see below)

Blow out whites, white and white greys pic 1

Blow out white, whites and white greys Pic 2

Some pixels are reporting grey/white dots and some darker shades of grey, but none are completely blown out (“whiter than white”) and none are black-black. This is a sign of good exposure, i.e. no blown out whites. There is some black in the picture.

 

Draw the histogram for the picture above:

Print off the picture below, and try your hand at drawing in the histogram for the picture above.

Blown out whites, whites and white greys

Blown out whites go off the histogram.

Below is an example of the nun’s picture overexposed, i.e. blown out whites. This is how the histogram looks on the 5D (and 7D). There are six faint white lines running vertically across the histogram.

Example of blown out whites going off the histogram

WHITES – The far right line (white arrow) is the edge of the histogram display. If values go past this point they disappear off the graph. They are “clipping”, which means there is no information…. just whiter than white. All detail is lost past that point.

The histogram squashes blown out whites up against the right side of the graph. (see white arrow). You can’t actually tell how much data you’ve lost. It just disappears off the graph and shows you a very thin spike along the edge.

GREYS – The greys of the nun’s skin tones are indicated by the yellow arrow. They are much too far to the right (over-exposed). Skin tones should be closer to the center of the histogram.

BLACKS – Also, see how the blacks (see black arrow) have moved away from the left edge of the histogram. In this case.the blacks won’t appear black but are “milky black”. The nun’s black robes won’t be black but dark, milky grey. Milky blacks are not good.

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