How to use the mosaic and blur risk checker
- Choose or drop an image, then drag to select the parts to hide. You can select several.
- Pick the method (mosaic, blur or solid fill), the strength and the text height, and the result and risk appear at once.
- When the risk is low and you are happy, save as PNG. If it hides too little, raise the strength or switch to a solid fill.
Why mosaic can be risky
Mosaic replaces each small cell with its average color, and blur mixes neighboring colors so they smear. Both reduce information by a fixed rule, so if only a few candidates for the original content exist, you can apply the same processing to each candidate and compare. This is especially true for digits, license plates and documents with a fixed format.
The smaller the cell compared with the text height, the more letter shape remains. This tool shrinks the original and the processed result to cells about one sixth of the text height, measures how alike they are, and sorts the value into three risk levels. A solid fill leaves no original information, so it has the lowest risk.
Basic rules when hiding personal information
For sensitive information, covering it completely with a solid color is safest. If you use mosaic, make the cells at least half the text height, and check again after hiding. It is better to hide once at sufficient strength from the start than to layer several weak passes.
Apart from hiding parts of the image, check whether information remains in the file name, location data in the photo, or signs and screen reflections in the background. The PNG this tool saves does not carry the original EXIF, but visible content stays. Make a habit of looking once more before publishing.
What to check when hiding
- Use a solid fill for important numbers and faces.
- Make mosaic cells at least half the text height.
- Make sure the hidden area is clearly wider than the text.
- Reopen the saved image and check it by eye.
- Check the background and reflections for other information before sharing.
FAQ
Is mosaic completely safe?
No. Mosaic and blur reduce information but do not remove it, and there are known cases where short numbers or strings in a known font and format were recovered. For important information such as ID numbers, account numbers, license plates and faces, covering them completely with a solid color is safer.
How is the risk calculated?
The original and the processed result of the selected area are reduced to cells about one sixth of the text height, and a correlation coefficient measures how alike they are. A higher value means more of the letter shapes remain. It is a simple estimate and does not decide whether recovery is actually possible.
Does the saved image keep location data?
This tool draws the image on screen and saves a new PNG, so the shooting location and device data (EXIF) from the original are not included. Signs, scenery and reflections visible in the photo stay, so check them yourself.
Notes & limitations
The risk level in this tool is a simple statistical estimate and does not guarantee that recovery is impossible. Images are processed only in the browser and are not sent to a server. You are responsible for any disclosure of personal information.