Photo Color Correction

Adobe Photoshop Tutorial

Pure White Background

When you have a pure white background on a picture, it can be superimposed on other images or is ready to be used effectively in a photo montage. It also makes a picture look more professional, blends well with text on webpages, and it reduces file size.

Dirty and discoloured backgrounds are very, very common, especially on the web, where pictures are the result of scans on cheap scanners which were never calibrated.

But even more expensive scanners which were calibrated don't always deliver pure white (or pure black) backgrounds.

Fortunately, these common problems are easy to solve in Photoshop, requiring little skill, time, or effort.

The photo of the kitten and kid below has a muddy background and a slight green tint. It should be pure white, but it looks dirty.

Copy the original photo (Right-Click-Copy)

New > File

Paste

Layer > New > Adjustment Layer > Levels > Auto

Just using the basic Auto Levels corrected most of the discoloration problem, taking away the green tint, but there is still a lot of "noise" in the background, and it is still not very clean. Noise not only looks bad, it also increases file size.

To remove the noise, crank up the Whites, by adjusting the third Input Level from 255 to 175, or until there is no noise left, even on the edges of the picture (far left and far right).

Change the midtone level to 1.2 for balance.

If you are unfamiliar with Photoshop, you might try to clean up an image like the one above by using the Magic Wand Tool. But this can take much longer, become more complicated, and doesn't usually deliver better results.

One-Click Background Fix with Eyedropper

One simple method to brighten or perfect the whitespace is to use the eyedropper tool in the Levels layer. Below the boxes on the right-hand side (OK, Cancel, Load, etc.), there is a row of three eyedroppers. These correspond to the Input Levels, i.e: the left one is for shadows; the middle for midtones; and the right for highlights.

Click on the highlights eyedropper (far right), and then click on the white background of your image. Photoshop uses the point where you clicked as the white balance reference point of 100% white. You should instantly see your picture get brighter and if you're lucky, you get an instant perfect white.

This method is best used when there is a minimal difference between the background and pure white. (When the original unedited image is pretty dark, often the change will "blow out" some details and compromise the general integrity of the photo.)

But because it works so quickly (and quicker than everything else), and it's so easy to test, it's often the best place to start when attempting background color correction.

The other issue is uniformity of the space you want white. If it has different shades of light gray, you often need to click on different parts of the background until it changes to an acceptable color. Same issue if the space is somewhat grainy. Try clicking on different spots.

How to do Photography with a 100% White Background

If you're a photographer as well as a photo editor, and want to avoid the post-processing needed to correct your photos, you want to know the technique of how to take pictures which are perfect coming out of your digital camera. Knowing how can save you lots of time and irritation.

The main trick is to beam light at a white background that is so bright it's impossible for it to be anything but 100% white. The way to do this is to use a white background and two lights.

Depending on the size of the subject for your photo, you can either use white board from a craft store, a white wall, or something else like white sheets. For larger subjects you can buy a background stand that holds paper rolls (similar to photo studios). Some photography supply stores like BH Video sell the paper roll stand as well as bright white paper (and lights).

Once you have that set up, you can position two lights to bounce off the wall or white background at a 45-degree angle behind the subject.

The light bulbs may need to have the right temperature otherwise your background will have a cast--a yellow cast is common. It may appear to be completely white when you take the picture but you find out soon enough it isn't when you load it into Photoshop.

Some digital cameras such as Canon SLRs let you know if a picture you just took has a 100% pure white background. The pictures you see in the viewfinder during playback flash where the white is pure.

If your lights aren't quite bright enough, you can sometimes get around the problem by changing the exposure of your picture to "blow out" the whites, especially when the color difference is very small. You may then have to compensate by darkening the images slightly (just change the Shadows setting in Levels, leaving Highlights alone).

But it's much more satisfying to get the picture right the first time with the right equipment so you never have to mess around with slightly dull backgrounds which take the edge off your image.

Good Canon digital cameras can be used with a digital file transmitter which beams pictures straight into Photoshop as soon as you take them. Then you know instantly if you got the perfect white background. But it's cheaper just to adjust your viewfinder/playback settings to see the Histogram and if the Whites are really white. Other cameras may offer the same features; consult your manual if you're not sure.