Through surfing the web by chance, I recently stumbled upon a very interesting, and more importantly, free, plugin. Mehdi Software’s Eraser Genuine plugin offers a color eraser with a new approach for users of Photoshop and Photoshop Elements. With a little practice, you can remove a color from your picture and replace it with another. This means you can change a blue sky to a green one in a few seconds.
II hear many of you already say “but Photoshop has a built-in selector and eraser feature”. True, but this plugin offers a remarkably clear and easy-to-use interface compared to the traditional eraser, and more ease of use compared to the advanced eraser tools, while producing quite good results. In addition, it’s barely more than half a megabyte, so you can safely give it a try.
A few words about installation. Eraser Genuine can be downloaded free of charge from the developer’s website, and after unpacking the file is called erasergenuine.8bf. You have to copy this into the Plug-In folder of your Photoshop, and after launching the application, you can see the plugin in the Filter/Mehdi menu.
During usage, remember a small but logical inconvenience. The plugin does not handle the usual Background layer, since it considers it locked. You have to duplicate the Background layer first. This takes about 2 secs: Double-click Background on the Layers palette, then click OK on the dialog that appears. That’s all! Now you can start removing any color and getting a transparent background in its wake. As if you cut a hole into the picture.
Eraser Genuine handles two colors: one to be erased and one to be preserved. The former is the background color in Photoshop, the latter is the foreground color. You can select these in a blink of the eye using the Eyedropper tool before using the plugin, but they can be specified later as well, on Eraser Genuine‘s user interface.
Let’s start erasing then! Click Filter/Mehdi/Eraser Genuine to open the plugin. The user interface is pretty usual. The preview image is on the left for tracking the results, and underneath you can set the zoom level. On the right, you have the controls. The first two color squares are the specified Erase and Preserve colors. Double-click those squares to display a color picker palette which allows color selection. Single-click a square to select it and apply changes to that color using the controls below.
The Color Model dropdown offers two color schemes that define the next three sliders as well. Using the HSB scheme, you can alter Hue, Saturation, and Brightness of the selected color. Let’s see an example. You want to cut out the blue sky from the picture, but other parts of the photo contain paler blue elements with a greyish tint. First, click the Erase square to specify the erase color. On the Hue slider, get the color roughly corresponding to the blue of the sky—it will be somewhere in the middle. Now set Saturation. In our case, we need a vivid blue, so we’ll use a high value. The rest of the blues in the picture are weak and greyish, so they separate easily from the bright blue, which will be the only one erased. Since we have a light blue sky, we set the Brightness slider to a high value as well, so that darker blues will be skipped.
When using the RGB scheme, the sliders affect the intensity of the color channels, Red, Green, and Blue. Drag each one to the left for darkening and to the right for lightening.
The next section, Opacity, is very important. This is where you set the intensity of removal for the colors closely related to the one specified above. The blue color of the sky is usually not of a single hue, but has gradients depending on exposure. This means that in order to erase it, you have to specify a range instead of one hue. Select Auto to have the plugin determine this range, but beware, most of the time it won’t give a good result. You’re better off with setting the Minimum and Maximum sliders yourself. Make sure the Minimum value is the lower of the two, because otherwise The erase and preserve colors will be swapped and you’ll keep what you wanted to discard. In the picture below, the sky is moderately light and contains relatively few hues. Set both slider to a medium value, with just a small difference, since the range you have to span is fairly small.
If you’ve done it right, the sky can be removed from the picture without erasing any other blue colors. You can fill the empty areas as you wish, or crop the remains and place them onto another background.
In the pictures below, we replaced the blue sky with a few color transitions. The top left picture is the original, while the other three are our creations.
Give Mehdi Eraser Genuine half an hour and it will repay the time and confidence invested. You’ll be able to crop complex shapes from pictures, saving a lot of time. And time, as you know, is money.
Mehdi Eraser Genuine can be downloaded from: