Day: January 17, 2010

Fixing Underexposed Shots in Photoshop

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As much as I hate the flash in my digital camera when it ruins a shot by firing when I don’t want it to, I hate myself more when it doesn’t fire because I’ve turned it off and then I discover later that I really should have let it fire. Does this ever happen to you? What do you usually do about it? I used to try Photoshop’s Auto Levels command (and rarely be happy with the results). Then, later I tried switching to the Auto Color command from Photoshop 7 (and still wasn’t happy with the results).

Then I learned how to travel back in time and turn the flash on!

OK, not really. But it was fun to say 🙂 And I have a trick to share that is almost as impressive when applied to an under-exposed picture.

Note: I originally learned this technique from the excellent book the photoshop book for digital photographers by Scott Kelby from New Riders Press (ISBN 0-7357-1236-0). I highly recommend it; it taught me more about Photoshop than all of the other Photoshop books I own combined 🙂

Anyway, here’s how the trick works:

  1. Use Photoshop to open an image in which you wish the flash had fired
  2. Duplicate the background layer (Control-J on PC or Command-J on Mac)
  3. Set the blending mode for the new layer to Screen:
    • Make sure your new layer is selected in the layers palette (click it)
    • Find the blending mode dropdown list at the top-left corner of the layers palette (it’s the one whose current choice reads Normal.
    • Choose Screen from the list.

Notice the difference? Pretty cool, huh? It really is like Photoshop magically turned on your flash via time travel 😉

TIP: If one screen adjustment layer still does not make the image bright enough, duplicate it (Control-J on PC or Command-J on Mac). The new layer will inherit the screen blending setting. Keep duplicating the layer until your image is bright enough…

TIP 2: If you add a screen adjustment layer and it’s not enough, but then add another and it’s too much, lower the opacity setting of the top layer (it’s the dropdown next to the blending mode one where you selected Screen). Start by trying 50%. If that’s not quite right, adjust the opacity up or down until it’s just right.

Here’s what the Photoshop help says about the Screen blending mode (in case you’re interested in what it’s actually doing):

Screen looks at each channel’s color information and multiplies the inverse of the blend and base colors. The result color is always a lighter color. Screening with black leaves the color unchanged. Screening with white produces white. The effect is similar to projecting multiple photographic slides on top of each other.

But you and I know what it’s really doing, don’t we? That’s right; it’s magically traveling back in time and turning on the flash when it needed to be turned on.

Shhh – I won’t tell. Ancient Chinese Secret, right? 😉

Quickly Whip Your Screen Into Shape For Viewing Images

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Have you ever worked really hard on an image, posted it, and then looked at it from another computer only to discover that it looks much too dark on that person’s screen? Or much too light?

Here’s a quick-and-dirty set of steps to get your monitor at least in the right ball park for displaying images with the right brightness and contrast.

calibration strip for brightness and contrast

If you don’t see the image inline with this post (hello, facebook), you can view it on my photography website.

The strip shows a range of greys from pure black to pure white. You should be able to see a clear difference between each shade of grey, ranging from pure black (left) and pure white (right). Along the top of the strips are alternate patches of black and dark grey. If it looks solid black to you (look very carefully), your monitor’s brightness setting is too low. Increase it until you can -just- perceive the difference between the grey and the black squares.

Also note that you might need to adjust both brightness _and_ contrast (if your monitor allows each to be changed independently) in order for all of the distinct shades to be seen.

Also note the important fact that this is not going to help at all to correct color problems if your monitor’s color settings are off; it’s only for getting the right brightness. For the color aspect of things, I highly recommend getting a hardware calibration device (like Pantone’s huey or X-Rite’s Eye-One); ESPECIALLY if you want to sell prints of your work.

Fixing Overexposed Shots In Photoshop

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I hate the autoflash on my digital camera. It never fails; I’ve spent a whole bunch of time framing a shot and getting the focus just right, concentrating on holding the camera steady because I forgot my tripod, well, you know the drill. So i take the shot and UP POPS THE FLASH AND DROWNS EVERYTHING IN A BLAZE OF WHITE! I’ve gotten to the point where I deliberately go out of my way to choose modes where I know it CANNOT come up and ruin my shot. But that does not do anything to save those images that I have already taken and had ruined by the stupid flash.

How about if I share something that does? (I originally learned this trick while reading the excellent book ‘the photoshop book for digital photographers’ by Scott Kelby (ISBN 0-7357-1236-0). If you find the following useful, you should seriously consider picking up a copy as there is much that it can teach you 🙂

Now, mind you, it’s not just my stupid flash that I hate for overexposing my pictures. I’m frequently mad at the sun for making things so darned bright. And at the sky for projecting light rather than reflecting it, and thus fooling my poor, simple light meter. Oops, I’m in danger of ranting, aren’t I?

Anyway, here’s how the trick works:

  1. Use Photoshop to open an image in which you wish the flash had not fired (or in which the sun was being somewhat over effusive)
  2. Duplicate the background layer (Control-J on PC or Command-J on Mac)
  3. Set the blending mode for the new layer to Multiply

    • Make sure your new layer is selected in the layers palette (click it).
    • Find the blending mode dropdown list at the top-left corner of the layers palette (it’s the one whose current choice reads Normal.
    • Choose Multiply from the list.

Notice the difference? Pretty cool, isn’t it? It’s as if Photoshop magically reached back in time and turned the flash back off 🙂

Here’s what the Photoshop help says about the Multiply layer blending mode and what it does:

Multiply looks at the color information in each channel and multiplies the base color by the blend color. The result color is always a darker color. Multiplying any color with black produces black. Multiplying any color with white leaves the color unchanged. … The effect is similar to drawing on the image with multiple magic markers.

Here’s what I say about it:

It should be called the miraculous way to fix that stupid flash in my camera 😉

TIP: If one multiply layer does not quite fix the overflash, feel free to add another one. And another one…

TIP 2: If you reach a point where the photo’s not quite right yet, but adding another multiply layer darkens the photo too much, try changing the opacity of the final layer to 50% (you can do this by changing the value of the Opacity dropdown which is right next to the Blending Mode dropdown in the Layers palette)