2.2.3.8 LevelsEffect Object

The LevelsEffect object specifies adjustments to the highlights, midtones, and shadows of an image.


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Highlight

MidTone

Shadow

Highlight (4 bytes): Specifies how much to lighten the highlights of an image. The color channel values at the high end of the intensity range are altered more than values near the middle or low ends, which means an image can be lightened without losing the contrast between the darker portions of the image.

Value

Meaning

0 ≤ value < 100

Specifies that highlights with a percent of intensity above this threshold SHOULD be increased.

100

Specifies that highlights MUST NOT change.

MidTone (4 bytes): Specifies how much to lighten or darken the midtones of an image. Color channel values in the middle of the intensity range are altered more than values near the high or low ends, which means an image can be lightened or darkened without losing the contrast between the darkest and lightest portions of the image.

Value

Meaning

-100 ≤ value < 0

Specifies that midtones are made darker.

0

Specifies that midtones MUST NOT change.

0 < value ≤ 100

Specifies that midtones are made lighter.

Shadow (4 bytes): Specifies how much to darken the shadows of an image. Color channel values at the low end of the intensity range are altered more than values near the middle or high ends, which means an image can be darkened without losing the contrast between the lighter portions of the image.

Value

Meaning

0

Specifies that shadows MUST NOT change.

0 < value ≤ 100

Specifies that shadows with a percent of intensity below this threshold are made darker.

Bitmap images are specified by EmfPlusBitmap objects.

See section 2.2.3 for the specification of additional image effects parameter objects.