Increase image DPI for print, with real pixels
OpenPixels (openpixels.app) is a free, open source photo enhancer that runs on your own device. To increase image DPI for a print, it enlarges the image 2×, 4× or 8× with an AI model, so there are enough pixels for 300 dots per inch at the size you want. The image is never uploaded.
Free, open source, no account, no watermark. Works offline once its model has downloaded.
What it means to increase image DPI.
A digital image has a width and a height in pixels. DPI is only what you get when you print it: the pixel width divided by the width in inches. A 1200-pixel-wide image printed 4 inches wide is 300 DPI; printed 8 inches wide, it is 150.
Many tools increase image DPI by changing a number stored in the file. That number does not add any detail. OpenPixels does the other half: it adds pixels, and it does not write a DPI number into the file. When a print shop asks for “300 DPI at 8 × 10 inches”, it needs 2400 × 3000 pixels, and that is what enlarging gives you.
How many pixels a print needs.
4 × 6 in
1200 × 1800 pixels. From 600 px wide, choose 2×; from 300, 4×.
8 × 10 in
2400 × 3000 pixels. From 1200 px wide, choose 2×; from 600, 4×.
A4 (8.3 × 11.7 in)
2480 × 3508 pixels. From 1240 px wide, choose 2×; from 620, 4×.
12 × 18 in
3600 × 5400 pixels, about 19 megapixels. From 900 px wide, choose 4×; from 450, 8×.
Any other size: multiply the inches by 300, divide by your image’s width, and pick the next multiplier up.
Increase image DPI in five steps.
- Open the app and press Choose a photo, or drop the image anywhere on the page.
- Under Size, choose the multiplier from the table above.
- Under What is it, keep Photograph, or choose Drawing or anime for an illustration or a logo.
- Press Enhance. The panel under the result shows the new size in pixels, such as 2400 × 3000, from 600 × 750.
- Press Save the photo and send that file to print, at the size you planned.
To increase image DPI for a whole set of prints, open Several at once: the same multiplier is applied to every image, and Download all as a ZIP gives you the results in one file.
It checks that the detail is real.
After it enlarges an image, OpenPixels shrinks the result back to the size you started with and compares it with your image. When the two still match, the panel says Faithful to the original: the detail was enlarged rather than invented, which matters on paper, where every flaw is larger.
Before you increase image DPI.
Largest print. The web app and the Windows and Mac apps hold the result near 40 megapixels, about 17 × 26 inches at 300 DPI; the Android app holds it near 16. Large posters are often printed at 150 DPI, where 24 × 36 inches needs about 19 megapixels. The app says how far a photo can go before anything runs.
Soft photos. Enlarging cannot recover detail that was never captured. An out-of-focus photo stays soft, only larger: try the image sharpener first.
Increase image DPI now.
It also enlarges photos in the browser, takes them to 4K, handles drawings and anime, and comes as software for Windows, Mac and Android.
Open OpenPixels →Before you open it.
What does DPI mean for a digital image?
DPI (dots per inch) is how many pixels are printed in each inch. A digital file only has pixels; the DPI is the pixel width divided by the print width in inches. A 1200-pixel-wide image printed 4 inches wide is 300 DPI.
Does OpenPixels change the DPI number stored in the file?
No. OpenPixels adds pixels; it does not write a DPI number into the file. Changing only that number leaves the image just as detailed, so a print shop that asks for 300 DPI at a given size is asking for enough pixels, which is what enlarging gives you.
How do I increase image DPI to 300 for a print?
Multiply the print width in inches by 300 to get the pixels you need, divide by the image's current width, and pick the next multiplier up: 2×, 4× or 8×. For an 8 × 10 inch print you need 2400 × 3000 pixels, so a 1000-pixel-wide image needs 4×.
Is it free?
Yes. OpenPixels is free, with no account, no watermark and no limit on how many images you process. The work is done in your browser, on your own device, and the image is never uploaded.
How large a print can it reach?
The web app and the Windows and Mac apps hold the result near 40 megapixels, which is a 300 DPI print of about 17 × 26 inches. A poster larger than that is often printed at 150 DPI, where a 24 × 36 inch poster needs about 19 megapixels.
Will a blurry photo print sharp at 300 DPI?
Enlarging adds pixels; it cannot recover detail that was never captured. A small, clean photo enlarges well. A photo that is out of focus stays soft, only larger.