2Pick your effects — grayscale, sepia, invert, blur, sharpen, brightness, contrast and saturation — and set the strength of each.
3Apply them all in a single pass rather than running the tool repeatedly, which is what accumulates visible damage.
4Download the filtered ICO file, and keep your original: it is the only undo you have.
ICO Filters FAQ
How does ICO Filters apply an effect?
+
Concretely, each bitmap in the stack receives the same filter so the icon stays visually consistent at every size it will be displayed at. You pick the effect and its strength and the transform is applied to the whole file at once.
Which effects are available?
+
Grayscale, sepia, invert, blur, sharpen, and brightness, contrast and saturation adjustment. They can be combined, and combining them in one pass is better than running the tool repeatedly.
Does the source format change how a filter looks?
+
It can. ICO is a container that holds several square bitmaps at once (16, 32, 48, 64, 128 and 256 px) so Windows and browsers can pick the size they need. Colour depth and the palette model in particular decide how smoothly a gradient or a blur can be represented.
Anything specific to ICO to keep in mind?
+
Yes — an ICO is a stack of square bitmaps, not one image, so operations apply to the stack and Windows still picks whichever size it wants. That is often the difference between an effect looking clean and looking banded.
Can I undo a filter after downloading?
+
No — the effect is baked into the output pixels, which is the point of applying it. Keep the original file; that is your undo. Grayscale and blur in particular discard information that genuinely cannot be recovered.
Can I apply the same look to a whole set?
+
Yes. One filter configuration is applied across the batch, which is how you get a visually consistent gallery rather than a set of individually-tweaked images that almost match.
What can I upload to ICO Filters?
+
ICO files containing one or several sizes, plus ordinary PNG or JPG artwork if you are building an icon rather than editing one. Windows .ico and browser favicon files are the same format.
Is there a file size limit on ICO Filters?
+
Yes: free accounts process images up to 25 MB each, which no icon file will ever approach — a full 16-to-256-pixel stack is typically well under 200 KB. Icons are the one part of the image family where the cap is genuinely irrelevant.
Will ICO Filters lower the quality of my ICO icons?
+
The sizes stored inside an ICO are lossless bitmaps, so the pixels themselves do not degrade. What actually decides how good an icon looks is whether the size the operating system asks for exists in the stack — a 256 px entry downscaled on the fly by Windows always looks worse than a real 32 px entry.
Can I run ICO Filters on several ICO icons at once?
+
Yes. Icon files are tiny, so a batch of them completes almost instantly; the round trip is dominated by the upload, not the processing.
Which sizes should the icon contain?
+
16, 32 and 48 pixels cover Windows Explorer and browser tabs; 256 covers large-icon view and modern shortcuts. Keeping all of them in one file costs almost nothing and stops the operating system from having to guess.
Does ICO Filters cost anything?
+
No. ICO Filters is free with no account, and the output carries no watermark — which matters more here than anywhere else, since an icon is a handful of pixels with nowhere to hide one.
