How to use
- Open sample.ico.
- Expect a 48 by 48 PNG.
- Expect the 16 and 32 images to be omitted.
Formula / how it works
sample.ico contains 16, 32 and 48 pixel PNG images. The page returns the 48 pixel one and says the smaller sizes are left out. The PNG is 48 by 48. A BMP-only ICO is refused, because this reader looks for a PNG signature inside the icon and will not pretend to decode the old DIB form. If you need the 16 pixel image instead of the 48, this page will not offer a size menu. It always takes the largest. Make a new ICO from a source image if you need a different set of sizes.
48 by 48 is a choice of largest, not a resize of the 16 pixel image. The small images remain inside sample.ico and are simply not the download. A BMP-only icon is refused rather than half-decoded. If you need 16, build another ICO from a 16 pixel source. This page will still hand you the largest.
Forty-eight by forty-eight is the largest image in sample.ico, and it is the only one this page returns. Sixteen and thirty-two stay inside the ICO and are not zipped out beside it. A BMP-only icon is refused because the reader looks for a PNG signature and will not half-decode a DIB. If you needed the sixteen pixel image, make a new ICO from a sixteen pixel source. This page will still give you whatever is largest. The sample was built from the bars at those three sizes so the check could see 48.
48 by 48 only. The smaller images stay in sample.ico. A DIB-only icon is refused. Ask for 16 by making a new ICO, not by a menu this page does not have. The check saw the largest PNG and stopped there.
Take the 48 pixel PNG and leave 16 and 32 inside sample.ico. That split is the feature, not a missing zip. A DIB-only file is a refusal, not a partial decode. If the art you need is the small size, build another icon from that size. This page will not grow a menu to pick 16. Largest is the rule, and the sample was built so largest means 48.
If the art you need is 16 pixels, this page is the wrong tool and it will keep telling you so by returning 48. Build a new ICO when you need the small size as the largest. sample.ico was made so the check could see 48 and could see that 16 and 32 were not the download. A DIB-only icon stops the page. That refusal is better than a broken PNG. Sixteen and thirty-two stay in the ICO. Forty-eight is the download from this sample, and the smaller sizes are not a second download.
Build a new set of sizes with image to ICO.
Worked examples
Largest image in sample.ico
Inputs: c2p-f: sample.ico
On this page, take sample.ico and press Extract PNG. Expect only the largest PNG from the ICO.
Result: Largest ICO image: 48×48 PNG. Smaller sizes in the same ICO are left out. BMP-only ICO files are…
Largest image again
Inputs: c2p-f: sample.ico
On this page, take sample.ico and press Extract PNG. Expect only the largest PNG from the ICO.
Result: Largest ICO image: 48×48 PNG. Smaller sizes in the same ICO are left out. BMP-only ICO files are…
Use cases
- Pulling the largest icon out as a PNG.
- Refusing a BMP-only ICO.
- Not offering a size picker.
- Checking 48 by 48 against the file that was packed that way.
Tips & limitations
- Largest wins.
- PNG signature required inside the ICO.
- The smaller images are still in the ICO. They are just not the download.
- Make a new ICO if you need a different set.
FAQ
Why 48 by 48?
sample.ico stores 16, 32 and 48, and 48 is the largest.
Where are the small ones?
Left in the ICO. This page does not zip them.
What about a BMP-only ICO?
Refused. The reader looks for a PNG payload.
Can I ask for 16?
No. Largest only.
Is the ICO uploaded?
No.
How was sample.ico made?
From 16, 32 and 48 PNG images of the bars, for this check.
48 by 48 is sample.ico. An ICO whose largest image is 256 will return that size instead.