![]() As a long time Word and WordPress user I became aware of several weaknesses in. I remember such fruitless discussions two decades ago, when I wrote 3 times a 1,000 pages book about. This is something that annoys me colossally. The problem, the developers explain that this is the way it was intended and have closed the Dormann bug report about it. The whole thing is discussed on Gitlab – and German security researcher Hanno Böck has covered in this German laguage article at site Golem. Possibly GIMP is removing the picture's alpha channel to generate the image for the thumbnail? This is clear when using a tool that leverages an image's thumbnail, e.g. When you save the image to a format that does not support alpha, but does support a thumbnail, that thumbnail also contains the unredacted picture.with ImageMagick "convert" or other tools) and they will have the original, unredacted photo. But in actuality, anybody can simply remove the alpha channel (e.g. From a UI perspective, the above picture sure seems that it has content removed. GIMP simply adjusts the alpha channel to make a hole through the picture. PNG), any "removed" picture information isn't actually removed. When you save the image to a format that supports alpha (e.g.There are two issues that affect GIMP when working with an image with an alpha channel: On Gitlab there is a thread GIMP doesn't properly remove image data when an alpha channel is supported which explains this in more detail. If such an image is stored and uploaded to social media sites like Twitter, this can lead to the fact that the supposedly deleted but only hidden image sections could be made visible later. Instead, an alpha channel is generated which hides the image section. vCWi80CH33ĭormann points out that the content of image sections will not be deleted by Gimp. You may think you've removed content, but it's just hidden. They simply create an alpha-channel tunnel through the content you think that you're removing. Preview) do not actually delete content from images with an alpha channel. Security expert Will Dormann took that up the in several tweets first after he became aware of the behavior. In my example image of my Cephalotus follicularis, also known as the Australian Pitcher Plant, it would take a very long time to get a perfect outline around the entire plant using the Eraser tool to do it all by hand.I became aware of this issue through a user hint in the discussion area of my German blog (thanks for that). You don’t have to use the Eraser tool in order to get a transparent background in GIMP. Other Methods for Erasing to Transparency There are also some filters that can cause GIMP to add an alpha channel, such as the Color to Alpha filter, which automatically turns all the pixels of a specific color into transparent pixels.Īdditionally, some image types like the PNG format, which is most commonly used for transparent images, may automatically include an alpha channel although JPEGs and other common file types may need to have one explicitly added. Whenever you create a new layer that has been filled with transparency, GIMP will automatically add an alpha channel to your image in order to handle the new transparent layer. ![]() There are also a couple of other situations where GIMP might automatically add an alpha channel for you. If you find that you’re working on an image that already has an alpha channel, you won’t need to bother with adding another one, and you can just skip right to Step 2 and start erasing to transparency right away. Click and drag to start erasing, and you’ll automatically be erasing to transparency! Step 2: Switch to the Eraser tool using the toolbox or by pressing the keyboard shortcut Shift+ E. The Channels panel now has four channels instead of the standard RGB ![]()
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