PhotoshopColor Correction Using Levels Apadted by Timothy Burns from a lecture by Barbara Chamberlin The tiny squares of color that make up all digital images are called pixels. Even the words on this page are made of millions of small black pixels. These pixels make up the myriad of colors that you see in an image. Many different pixels in images create the illusion of light, shadow and depth. The picture below is a close up of pixels. In Photoshop you can zoom into any image in and see the pixels. You can use the zoom tool to magnify images to see the pixels for yourself. When using Photoshop you can correct the color in the pixels by adjusting the levels of an image. By adjusting the level of the shadows, midtones, and highlights, you can change the visual impact of an image. Channels and Levels For this example we will use this image of two birds on a branch: 1. This is an RGB image. This means there are three channels of color to make up this image, a red channel, a green channel, and a blue channel. Making changes in the levels of these channels make the image more pleasing to the eye. The color levels are adjusted by increasing or reducing the amount of shadows, midtones, and highlights in each of the three color channels. Below is the same picture of the birds with the levels adjusted. 2. The image looks a much better with its color levels adjusted. Now let me show you how to color correct photos using Photoshop. Macintosh quickkeyes are highlighted RED, and PC quickkeyes are highlighted BLUE. Adjusting Color Levels 1. Open an image in Adobe Photoshop. I am going to use this image of three fire pits (barbeques). You can use this image also. Click the image and drag it to your desktop. 2. Choose Edit->Images->Levels, or just press Command L / Control L 3. The levels window will appear. This is where the color levels are adjusted. The graph in the middle of the level window is a histogram. A histogram graphs the number of pixels at each brightness level in an images (this definition is straight from the Photoshop user guide).The black triangle at the bottom left of the histogram indicates shadows, The gray triangle indicates midtones, and the white indicates highlights. 4. Click on the channel pull-down menu. This shows four things: the RGB channels , only the red channel, only the green channel, only and the blue channel. To move through the channels with ease use these quickkeyes: For the RGB channel press Command ~ / Control ~ For the Red channel press Command 1 / Control 1 For the Green channel press Command 2 / Control 2 For the Blue channel press Command 3 / Control 3 5. Now we are going to make changes in the levels in each of the channels. Select the red channel. Move the black triangle to the point where the values increase, do the same with white triangle. If you make a mistake hold down Option / Alt, the cancel button will become reset, this button will undo all changes made in the levels window. 6. You will notice a change in the image. Don't worry if it looks strange, only the red channel has been adjusted, when all the channels are adjusted the image will look a whole lot better. 7. Now repeat step #5 for the remaining two channels. 8. Adjust the gray triangle for each of the color channels to get the midtones just the way you want. Now that you have adjusted all the color levels, Click OK. To see the difference between your start and finish choose Edit->Undo Levels, or press Command Z / Control Z. This toggles your changes... on... and off. Auto Levels Now that you know how to adjust color levels, you know what Auto Levels do. Auto Levels adjusts color levels with a mouse-click. But Auto Levels does not fix all images with ease. For example, the image on the bottom left is the original the one on the bottom right is the Auto Levels correction. To see the difference between your start and finish choose Edit->Undo Auto Levels, or press Command Z / Control Z. This toggles your changes... off... and on. Sometimes auto levels works perfectly but don't rely on it. The auto correction makes the sky look alien, this is one of the reasons why you should manually correct the colors of images before you see the auto levels to get the best result. Auto Levels works the best for images with a wide range of color. So if auto levels don't work adjust the levels yourself. Back to Online Seminars