Correcting underexposed photo - RAW exposure adj or PS

[mfrobinson]

when using the exposure adjustment to brighten an underexposed picture, is it the same as increasing the ISO of the digital negitave or will it change colors the same way the picture will change when you use "adjust fill flash" in photoshop elements? Which way is better?

[ohenry]

It is always best to get your exposure correct in the camera so as to minimize post exposure processing. Having said that, when post processing you should adjust your exposure first then adjust any color corrections as needed.

[PacAce]

when using the exposure adjustment to brighten an underexposed picture, is it the same as increasing the ISO of the digital negitave or will it change colors the same way the picture will change when you use "adjust fill flash" in photoshop elements? Which way is better?

If possible, try to get all or most of your exposure correction done in the raw converter program instead of in the the photo editor such as PS. You can then fine tune the exposure with levels or curves later in the photo editor if required.

[mfrobinson]

Thanks for the responses - I aggree the photographer should get it right the first time but it sounds like using the exposure setting on the RAW processing is not too bad of an option.

[maderito]

when using the exposure adjustment to brighten an underexposed picture, is it the same as increasing the ISO of the digital negitave or will it change colors the same way the picture will change when you use "adjust fill flash" in photoshop elements?

I wanted to comment on your main question about ISO. I can't quote sources on the following, so take it for what it's worth. :?

I assume you are talking about adjusting "exposure" in RAW processing.

Setting ISO in the camera changes the gain in the CMOS image capture electronic circuitry which in turn governs in part how much noise (versus true signal) is in the image. The resulting so-called "digital negative" and its associated ISO cannot be changed after the fact.

Because of that limitation, adjusting "exposure" during Adobe Camera RAW processing changes the RGB values of individual pixels, but not the fundamental signal-to-noise ratio of the original data. The noise is there - and it's up to you whether to minimize its appearance (e.g. keep dark areas of the image dark, use post processing noise reduction techniques, etc.).

Adjusting exposure during RAW processing simply moves all tonal values (individual RGB numbers) up or down equally without changing their relationship to one another, as long as you don't clip them. In PS image editing, e.g. brightness/contrast adjustment, you distort and possibly merge RGB tonal values - for better or worse depending on your goal.

I second PacAce's advice.