Any image, at 4K size.
Drop an image and choose 4K UHD or DCI 4K. The tool resizes it to 3,840 or 4,096 pixels on the longer side, keeps the aspect ratio and saves it as JPG or PNG. It runs in your browser; nothing is uploaded.
Choose an image.
Resizing changes the number of pixels, not the detail: a small photo enlarged to 4K is larger, not sharper. The tool works on any image, from a product photo to a screenshot.
Resized, nothing generated.
- Method
- The image is redrawn at the new size with the browser's high-quality smoothing; no pixels are invented
- Sizes
- 4K UHD: 3,840 pixels on the longer side (3,840 × 2,160 for a 16:9 image); DCI 4K: 4,096 pixels
- Aspect ratio
- Kept: nothing is cropped or padded
- File
- JPG at 92% quality, with transparent areas turned white, or PNG, lossless and with transparency
- Upload
- None: the image is read and saved in your browser
Sharpen the detail for zoom.
The upscaler in the Herofab app doubles or quadruples the resolution of a product photo and sharpens what the photo holds, so buyers can zoom into fabric and stitching. It cannot recover detail the photo never recorded, and it uses credits.
About this tool.
Does this free tool need an account?
The first successful use of each free tool is available without an account. If prompted to continue using it, create a free Herofab account. Files are processed in your browser and are not uploaded.
Is my image uploaded?
No. The file is read and processed inside your browser; nothing is sent to a server.
What resolution is 4K?
4K UHD, the resolution of 4K TVs and monitors, is 3,840 × 2,160 pixels. DCI 4K, the cinema standard, is 4,096 × 2,160 pixels. For an image with another aspect ratio, the tool sets the longer side to 3,840 or 4,096 pixels and scales the shorter side to match.
Does converting to 4K make an image sharper?
No. Resizing fills the new pixels by smoothing between the existing ones; it does not add detail. A photo 1,000 pixels wide enlarged to 3,840 pixels gets no sharper and looks soft at 100% zoom. Above four times the original size, edges look visibly soft and the tool says so.
Which format should I choose?
JPG for photos: much smaller files, saved at 92% quality, with transparent areas turned white. PNG for graphics, screenshots and images with transparency: lossless, with larger files.
Can an image larger than 4K be reduced to 4K?
Yes. An image wider or taller than the chosen size is reduced so that its longer side is exactly 3,840 or 4,096 pixels, with the aspect ratio kept.
Does the tool use AI?
No. The image is resized with the browser's own smoothing; nothing is generated or added. The upscaler in the Herofab app is a separate tool that uses credits.
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