How to upscale an image to 4K, 8K or HD

These are the standard 16:9 screen sizes:

• HD (720p): 1280 × 720, about 0.9 MP.
• Full HD (1080p): 1920 × 1080, about 2.1 MP.
• QHD (1440p): 2560 × 1440, about 3.7 MP.
• 4K UHD: 3840 × 2160, about 8.3 MP.
• 8K UHD: 7680 × 4320, about 33.2 MP.

Divide the target by the upscale factor. These are the smallest 16:9 sources that reach each size with one run:

• 4K with Upscale 4×: 960 × 540 or larger.
• 4K with Upscale 8×: 480 × 270 or larger, such as a small thumbnail.
• 8K with Upscale 4×: 1920 × 1080 or larger. A Full HD frame becomes exactly 7680 × 4320.
• 8K with Upscale 8×: 960 × 540 or larger.
• For a portrait phone wallpaper, swap the numbers: 2160 × 3840 for 4K.

Many free HD or 4K converters only resize. The file then has 3840 × 2160 pixels, but the extra pixels are averages of their neighbours, so it looks exactly as soft as the small image did, just larger. On a 4K monitor or TV that softness is obvious.

An AI upscaler draws the larger image instead: clean continuous edges and fine texture that follows the photo, such as foliage, stone and fabric. It is still the same picture, with the same composition and colours.

Start from the largest copy of the image you have. If it shows grain or compression blocks at 100 % zoom, run Enhance first so they are not enlarged.

Choose the factor: if your image is at least a quarter of the target width, use Upscale 4×; if it is between an eighth and a quarter, use Upscale 8× (2 credits). Upload, compare and download.

Crop to 16:9 (or 9:16 for a phone) and, if needed, reduce to exactly 3840 × 2160. Reducing a slightly larger result is better than enlarging a slightly smaller one.

Landscapes, cityscapes, architecture and nature photos make the best 4K wallpapers, because the model adds the kind of texture they are full of. Portraits work too; faces are not reshaped, but a face that is only a few dozen pixels wide in the original stays soft.

Small text such as signs and captions stays as soft as in the original, because the model does not guess letters. Screenshots with interface text are better kept at their native size. Video is not supported: PhotoRescue works on still images only.

You get 3 free credits a day, with no sign-up and no card. One photo with one tool uses 1 credit; Upscale 8× uses 2. Free uploads can be JPG, PNG or WebP up to 3 MB and 8 MP, and free results carry a watermark. Pro ($9.99 a month, 200 credits) and Pro+ ($19.99 a month, 500 credits) remove the watermark and accept uploads up to 20 MB and 30 MP. Uploads and results are deleted within 24 hours and are never used to train AI.