The black boxes are a display glitch, not a permanent mark on your image

When you use the lasso fill tool in Krita and see large black rectangles appear around your selection, you are looking at a rendering issue in how Krita displays the selection outline on screen. The black boxes do not appear in your actual image file — they are part of Krita's interface showing you where the selection boundary is. The problem usually happens when Krita's graphics rendering gets confused about how to draw the selection indicator, especially on certain graphics cards or with specific display settings.

This is a known issue that has appeared in different Krita versions, particularly when using the lasso tool with certain brush settings or on systems with older graphics drivers. The boxes themselves are harmless — your fill operation will work correctly, and when you save or export your image, the black boxes will not be there. They are only visible while you are working in Krita.

Key Takeaways

  • Black boxes around a lasso selection are a display problem in Krita, not damage to your actual image file.
  • The issue usually appears when Krita's graphics rendering system struggles to draw the selection outline smoothly.
  • Updating your graphics card driver or switching Krita's rendering backend can often fix the problem.
  • If the boxes persist, deselecting and reselecting the area, or switching tools and back, usually clears them from the screen.

Why the rendering glitch happens with the lasso tool specifically

The lasso tool creates a freehand selection boundary that can be complex and irregular, unlike the rectangle or circle selection tools which draw straightforward geometric shapes. When Krita tries to display this complex outline on your screen, it has to redraw it constantly as you move your mouse or make changes. If your graphics card or Krita's rendering system cannot keep up with these constant updates, the selection outline fails to draw cleanly, and you see black boxes or other visual artifacts instead.

The problem is more common on systems with integrated graphics (graphics built into your CPU rather than a separate graphics card) or when your graphics driver is outdated. Integrated graphics have less dedicated memory and processing power for rendering, so they struggle more with complex, constantly-updating visuals like a detailed lasso selection outline.

How to fix the black boxes when ready

The fastest fix is to deselect your current selection and then reselect it. Go to Select in the menu bar, then click None to remove the selection. Then use the lasso tool again to create a fresh selection. Often the black boxes will not reappear on the second attempt, because Krita's rendering system has reset.

If that does not work, switch to a different tool (like the paintbrush or eraser) and then switch back to the lasso tool. This forces Krita to reload how it is displaying the selection. You can also try pressing Ctrl+H (or Cmd+H on Mac) to toggle the selection outline visibility off and on, which sometimes clears rendering errors.

Changing Krita's graphics rendering settings

Krita has different ways it can render graphics to your screen, and some work better than others depending on your hardware. Go to Settings in the menu, then Configure Krita, then Display. Look for the Renderer option. Krita usually defaults to OpenGL, but you can try switching to Angle or Vulkan if your system supports them.

After you change the renderer, Krita will ask you to restart. Once it restarts, try the lasso tool again. A different renderer sometimes fixes rendering glitches because it uses a different set of graphics instructions to talk to your graphics card. If one renderer causes black boxes, another one might not.

Updating your graphics driver

Your graphics driver is the software that lets Krita communicate with your graphics card. Outdated drivers often cause rendering problems, including the black box issue. The steps to update depend on your graphics card manufacturer.

If you have an NVIDIA card, go to nvidia.com/read/driverDetails.aspx, enter your graphics card model, and read the latest driver. If you have an AMD card, go to amd.com/en/technologies/radeon-drivers and find your card model. If you have integrated Intel graphics, go to intel.com/content/www/us/en/support/detect.html and let Intel's tool detect your system and find the right driver. After downloading, run the installer and restart your computer. Then test Krita again.

When the black boxes mean something else

In rare cases, black boxes in Krita are not a rendering glitch but an actual part of your image. This happens if you accidentally filled a selection with black color, or if a layer below your current layer has black content showing through. To check, look at your Layers panel on the right side of the screen. Make sure you are working on the correct layer, and that the foreground color (shown in the toolbox on the left) is not set to black.

If you filled with black by mistake, press Ctrl+Z to undo the fill operation. You can also click on the foreground color square in the toolbox and choose a different color before filling again. This way you can tell when ready whether the boxes are part of your actual image or just a display problem.

Frequently Asked Questions

Will the black boxes save into my image file?

No. The black boxes are only visible on your screen while you work in Krita. When you save your file as a Krita project (.kra) or export it as PNG, JPG, or any other format, the boxes will not be included. They are part of Krita's interface, not your actual image data.

Does this happen with other selection tools?

The black box glitch is most common with the lasso tool because its selection outline is complex and irregular. It can occasionally happen with the free select tool or when making very detailed selections with other tools, but it is much rarer. If you see black boxes with every selection tool, the problem is more likely your graphics driver or Krita's renderer setting.

What if changing the renderer makes things worse?

Switch back to your original renderer by going to Settings > Configure Krita > Display > Renderer again. You can also try disabling hardware acceleration entirely by looking for an option like "Enable OpenGL" or "Use GPU Acceleration" and unchecking it, though this will make Krita slower overall. If problems persist, updating your graphics driver is the next step.

Does Krita have a bug report for this?

Yes, this issue has been reported multiple times on the Krita bug tracker at bugs.kde.org. If you search for "lasso black boxes" or "selection rendering", you will find existing reports. If your situation is different from those reports, you can file a new one with details about your graphics card, driver version, and Krita version.