Topic Author
Posts: 795
Joined: Tue Jul 03, 2001 3:28 am

Canon RAW Question

Wed May 26, 2004 6:19 am

Will changing the exposure compensation in the RAW software have the same effect as changing it in camera at the time of the photograph? Of course, this assumes there are no blown highlights.

For example, you take a photo and the exposure compensation is set to -1. If you took the same photo at EV 0, and changed it afterwards with the RAW software to -1, would it be the exact same as if you took it originally with the exposure compensation set to -1?

Am I making sense?  Smile

Does this also apply to WB as well?
Jet City Aviation Photography
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RE: Canon RAW Question

Wed May 26, 2004 6:21 am

You can adjust the WB afterwards without any loss of quality, but not the exposure. It works up to a certain degree, but there are limits. One half up or down shouldn't be a problem though.

Even a broken clock is right twice a day.
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RE: Canon RAW Question

Wed May 26, 2004 6:27 am

No its not exactly the same - there will be a small loss of quality if you try and increase the exposure (ie fix an underexposed photo). This is because the more light hitting the sensor, the better the signal to noise ratio.

For instance, a patch of neutral grey underexposed by one stop and corrected in conversion will show slightly more noise than the same grey patch correctly exposed. By the same logic, the extra noise will be most noticeable in the shadow areas.

In practice, working with a full size image, I would say up to one stop compensation is probably unnoticeable in a final print - beyond that, the noise will become evident in the shadows.

Conversly reducing exposure should show no loss in quality (though, as you correctly state, youcan't recover detail that was never recorded).

White balance can be adjusted with absolutely no loss of quality as the RAW image is actually B&W - colour is only applied when the image is processed - either in camera for .jpg or in software for RAW.


Colin K. Work, Pixstel
Topic Author
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RE: Canon RAW Question

Thu May 27, 2004 3:36 am

Thank you both for the replies, very much appreciated!
Jet City Aviation Photography
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RE: Canon RAW Question

Thu May 27, 2004 5:42 am

Colin, as always a very informative answer to a specific technical question.


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