Question

GIMP: color to transparency - this is how it works

Answer 1

Here's how to make a color transparent in GIMP
1st step:
2nd step:
3rd step:
4th step:
5th step:
6th step:
7th step:
quick start Guide

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The GIMP allows you to make certain colors in your images transparent. We'll show you how to do it..

The GIMP allows you to select certain colors in your image and make them transparent. This method is also used for green screens, for example. How exactly to make colors transparent in GIMP is explained in the following guide.

Here's how to make a color transparent in GIMP

Follow our step-by-step instructions or take a look at the quick start guide .

1st step:

To make a color transparent in the GIMP, use the Color To Alpha feature . This tool allows you to move a single color within an image - or a range of similar colors - into the alpha channel, resulting in transparency. To access this menu, open up " level " and then choose to " transparency option" " Color to Alpha ".

2nd step:

Once opened, you should find that a large part of the image on your canvas becomes partially transparent. This is because the Color field on the Color To Alpha menu is white by default (as indicated by the white stripe in the menu). This means that the white component of all colors in your image is reduced to transparency based on a scale that indicates the white component of the color. To select the color that you want to make transparent in the GIMP, click the eyedropper icon in the "Color to Alpha" window. It's the first entry at the top of the list, next to the white stripe. With the eyedropper selected, click the area of ​​your image that contains the color you want to make transparent. Alternatively, you can click on the white stripe to enter a color code manually. For this example image we are going to make the color of the flower transparent, so we click on the area of ​​the image where the flower is located.

3rd step:

Since the color composition of images can be very nuanced, it's likely that you don't need to make just a single color transparent. Ideally, you want to make all similar colors transparent as well. For example, the color of the flower in our picture is pink - but there are many different shades that need to be made transparent as well. This is where the Color to Alpha tool really comes into its own . Select the middle pipette symbol next to " Transparency threshold " in the menu . Use this tool to find the lightest area Of your image that contains the color you want to make transparent.

4th step:

Now that you've told GIMP which pixels you want to be completely transparent, you need to tell it which pixels you want to remain completely opaque . To do this, click on the last pipette symbol next to " Opacity threshold ". Then click on an area of ​​the image that contains colors that you want to remain completely opaque. Since your image will most likely have many different colors in it that you want to remain opaque, you may need to pick multiple colors to see which one gives the best result. You can also click and drag across your image to see how each of these colors reacts in real time.

5th step:

At this point you are almost done. However, as you can see in our sample image, there are some areas that are also transparent next to the flower. This is where the threshold value sliders come into play. In the " Color to Alpha " menu you will see two sliders: Transparency Threshold : This controls the intensity of the transparent areas. As you increase this value, more colors are picked up from the spectrum and made transparent. Decreasing the value has the opposite effect. Opacity Threshold : This controls the intensity of the opaque area. As you increase the value, more colors in the selected spectrum become opaque. Decreasing the value has the opposite effect. Now adjust these two sliders to optimize your selection. The values ​​you should use vary from picture to picture. There's no real formula for it, so just give it a try and adjust the sliders until you get the result you want. However, depending on how complicated your image is, you may not be able to get a really optimal result even with the sliders.

6th step:

When you're happy with the adjustments, simply click the OK button to apply your changes and make the chosen color transparent.

7th step:

Unfortunately, there is no perfect way to make a color transparent in the GIMP. Regardless of the technique you choose, you will most likely end up with imperfections, as is the case with our sample image. Once you've eliminated the base of the colors that you want to make transparent, you can use the Eraser tool, for example, to mark all the pixels that you still want to make transparent. You can also go back and color in any pixels that were supposed to remain opaque but may have been made transparent.

quick start Guide

1. In the GIMP menu bar click on " Layer " and after " Transparency " select the option " Color to Alpha ".
2. The " Color to Alpha " dialog box opens. If you click on the first eyedropper icon on the right, you can choose a color in your image and make it transparent .
3. If you now click on the second pipette symbol on the right edge of the window, you can select another color . This should be lighter than the previously selected color, as this determines which color spectrum should be made transparent.
4. Now click on the last eyedropper icon on the right to select a color in your image that should not be made transparent . This helps you to make areas that were accidentally transparent again visible. You may need to experiment a little here until you get the best result.
5. To adjust your selection even more precisely, you can use the " Transparency Threshold " and " Opacity Threshold " threshold sliders to change the values. The first slider changes the areas that are made transparent and the second changes the intensity. If you change the values ​​a little now, you can refine your result further.
6. Then, in the window " Color to Alpha " to " OK " to save your changes.
7. If you now select the " Painting tools " menu item in the " Tools " category , you can use the eraser to make other areas transparent or to color transparent pixels again with the brush.

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