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Basic exposure effects?
Posted: 2016-12-09T05:50:04-07:00
by mrburnzie
Hello!
How do I achieve exposure with imagemagick?
Examples with the apple exposure effect:
https://postimg.org/image/52350k2xl/
https://postimg.org/image/5s5y2wiu7/
Thanks!
Re: Basic exposure effects?
Posted: 2016-12-09T10:55:16-07:00
by fmw42
We do not know what apple is doing. But you can get exposure changes in a number of ways. If on Unix (not windows), I have a script calle exposure and another called xposure at the link below. Otherwise, use -brightness-contrast or -level.
Please always provide your IM version and platform.
Re: Basic exposure effects?
Posted: 2016-12-09T13:07:42-07:00
by snibgo
I don't know what Apple is doing.
For a close approximation to changing the cameras exposure, assuming you use sRGB colorspace, add or subtract a certain amount. Depending on many factors, 10% of quantum is approximately equivalent to one stop on the camera.
Code: Select all
convert in.png -evaluate add 20% out.png
This brightens the image by approximately two stops.
(This may not be entirely accurate. You would need to test your camera, photographing a gray card at different exposures to see if 10% is correct, and to see whether the same amount can be used across the entire range.)