How to determine overexposed and underexposed areas using Photoshop

note: This lesson will be  useful for photo retouchers, who will be dealing with partially overexposed image, where important to see exactly where overexposed areas is.  For example, if you need to get completely white background, etc.

Couple years ago we found that a histogram on the camera or different software’s don’t show overexposed areas correctly. Here is why: camera histogram will use JPEG to evaluate, even if you shoot RAW. So, it is inaccurate by definition.
When I’ve  tried to find the answer in Internet, I get no luck, there are only tutorials and lessons how to fix this overexposed areas in Photoshop, but nothing about how to  find these areas correctly.

So this tutorial about how to find and determine overexposed and underexposed areas using Photoshop.

Look at this image:

image-with-overexposed-areas

Some areas are overexposed here. Let’s check where are these areas:

Create new fill or adjustment layer -> Curves

Create new fill or adjustment layer

Create new fill or adjustment layer

Select Curves...

Select Curves...

Than drag the graph from the left lower corner to the right lower corner:

Curves in photoshop

Curves in photoshop

Your image become dark with few white spaces. This white areas are truly overexposed. Meaning you have no color information there (white, no details at all) , and it can’t be recovered.

Real overexposed areas

Real overexposed areas

Similar you can find truly underexposed areas on you image. Look at this image:

Determine underexposed images

Determine underexposed images

Here are plenty dark spaces. Do they underexposed? Yes. Can they be recovered? Let’s check.

Create again new fill or adjustment layer -> Curves.

And  drag the graph from the right upper corner to the left upper corner:

Determine underexposed areas on the photo

Determine underexposed areas on the photo

What do we see? There are no underexposed areas on this picture. So, now you can create a pseudo HDR (HDR – like look from the one exposure, instead of several) image form it, and everything will look good, with some noise added on dark areas.

No underexposed areas

No underexposed areas

Here is another example with underexposed areas:

Picture with underexposed areas

Picture with underexposed areas

This black spots are real underexposed. There are no details  and color information there, except black. There is no way you can fix such image. (if you find it  should be fixed, of course:-)

Underexposed areas

Underexposed areas

If you know the better and faster way to find  “truly” overexposed and underexposed areas on images, please share with me.

Please visit our Photo Portfolio web site

9 comments to How to determine overexposed and underexposed areas using Photoshop

  • Sean

    Use the Alt (Option) Key as you drag the sliders and you will see the same behavior. This occurs for the levels dialog box as well. It can be helpful even if none of your image is over or underexposed because you can set the sliders to just the point where you would begin losing information.

  • Randy Sellet

    Thanks, this is a very fast, easy way to find the areas in a photo not worth exploring or optimizing. This will save me time and effort. Excellent help advice!

  • I believe a simpler way is to use your eye dropper and take readings of your raw capture. You can use RGB or if the image is going to print
    use CMYK. Take several readings in highlights, 1/4 tones, midtones, 3/4 tones, and shadow areas. If you shot by the numbers, this should go
    quickly.

  • John Wheeler

    Here is a link to my blog where I posted a method for dynamic detection of over / under exposure very similar to Adobe Lightroom and Adobe Camera Raw http://jkwphoto.blogspot.com/

    I plan to post other methods on my blog if there is interest.

  • dbltapp

    Using CS4 and either jpg or raw images, set them to open in Adobe Camera Raw. After opening an image, in the histogram panel (upper right), click on the triangles in the upper left and right corners. Overexposure shows up red in the image, underexposure blue. Adjust Exposure and Recovery to fix things.

    Works identically in LightRoom.

  • The very basics we forget most of the time, in fact it is the first to be understood. Good information provided here. I like it.

  • [...] More detailed screen shots of this step you can find on my previous lesson How to determine overexposed and underexposed areas using Photoshop [...]

  • ML

    Hi. Thanks for your solution. Definitely there is an interest, so please post more tutorials!

  • Am I the only one who thinks that some little underexposed or overexposed spots of the background are inevitable and thus normal?

Leave a Reply

  

  

  

You can use these HTML tags

<a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <strike> <strong>