Advantages between lightening methods for our dark pictures?
What choices are better for which cases?

Chief among the tools not generally suited to a photo are:
Colors > Adjust > Brightness/Contrast

The reason is that the tool is destructive to image information. When you increase the brightness you add some increment to every color value, lets suppose 30. A color of 210 is increased to 240. However, a color of 230 is increased to 260 and a color of 240 is increased to 270. Since you have a maximum of 255 for the value of a color both colors are clipped to 255. Thus, what was originally a difference of 10 units in highlights (240 - 230) becomes zero. The color difference is permanently destroyed and cannot be recovered. The same happens in shadows when you reduce the brightness.


The permanent damage can be overcome by using the effect as an adjustment layer. Similar things can happen if you use blend modes for manipulating image brightness.


It makes much more sense to use Colors > Adjust > Gamma Correction for manipulating image brightness because this is much less destructive. Only extreme values of the control (not used in practical adjustment) can damage the photo.

Even better is to use the:
Colors > Histogram Functions > Histogram Adjustment

With this filter you receive information what information you are losing. Under the Low and High Clip Limit controls are little windows showing what fraction of image information you are discarding. Generally, this should be 0.1% or less. Depending on subject (e.g. a shiny forehead) you may need a lower number still. You can actually reproduce the Brightness/Contrast example I gave above with this tool. Press Reset then set 225 (255 - 30) for the High Clip Limit and 30 for Output Min. Compare histograms before and after and check the information loss. If you are going to be adjusting a lot of photographs I would strongly recommend becoming very familiar with this tool.

You will learn to make adjustments in a principled way with the histogram as a guide to how information is distributed in your image. (This takes a bit of practice since the histogram depends both on image exposure and on image subject.) For example, the histogram can help you understand why the image looks as it does (e.g. too many dark tones and too few light, not much midtone information, etc.).

Clip Limits let you set the image to use the full image brightness range,

Gamma sets overall brightness by adjusting the balance between shadows and highlights,

and Midtone Expansion/Compression compensates for the information distribution between Midtones on the one hand and shadows and highlights on the other.

This guy (as Porter would say) is the photographer's friend.

This is not really an answer to the question you asked. However, I think you asked the wrong question and could benefit from my advice to do something else :) In image adjustment, except by painting in, you cannot create any information that is not in the image. However, rearranging what information is there makes an amazing difference to the image because human vision perceives different kinds of image information in different ways. You need to put the information where the eye can see it best (or, if it is noise, hide it where the eye can't see it). In doing this, your guideline should be never to discard information since there is no bringing it back later, no matter how much you manipulate. In my experience a great many of the "can you help me fix this photo?" posts are self-inflicted problems. At some early stage of image acquisition someone did something that discarded information. By the time the question is asked it is rather too late to do anything truly optimal (though of course improvements are generally possible with PSP tools). -Kris

Great post, Kris, very helpful. I've been addicted to adjusting digital images with Brightness/Contrast, along with Gamma. I did it strictly by appearance, but it does look like some images suffer more losses by use of Brightness/Contrast. I am going to replace the Brightness/Contrast tool button with that of Histogram adjustments. Chuckle. Do you know of a specific tutorial that may demonstrate your suggestions? Do you have a favorite tutorial for Histogram Adjustment?

Frankly, no. The problem is that everybody wants a simple "just follow these steps" tutorial, but it doesn't work like that. Normally, you might say something like "if there is a big dark peak, increase gamma". This would work well for a landscape where no large dark regions are expected but would fail for a head to waist shot of a woman in that little black cocktail dress number. In other words the histogram depends on both exposure and image content. Without understanding the scene content it is not possible to give generic advice. The best thing I can suggest is to keep using the tool. After a while you will begin to "get it" so to speak. One thing to try is to push the Low and High Clip limits close together and drag them up and down together with Autoproof on. It gives you a feel for what portion of the histogram corresponds to which region of the image. There are a couple of tricks such as: (1) following up with Clarify after compressing midtones, and (2) reducing Output Max and following up with Clarify to fake missing highlight detail (see my reply to Tina Cawthorne's Editing Black & White Photo post).

Though they are not about histogram adjustment, you may find my tutorials on Detail from Shadows and Fixing Flash Photos to be of some interest. -Kris