Upscale images online

Image upscaling: increasing resolution without AI

Image upscaling increases the pixel dimensions of an image — making a 500x500 image into a 1000x1000 or 2000x2000 version. The challenge is that upscaling cannot create detail that does not exist in the original. Every new pixel must be interpolated (estimated) from the surrounding original pixels, which is why upscaled images can look soft or blurry.

This tool uses multi-pass bicubic interpolation, which produces smoother results than single-pass upscaling. Instead of jumping directly from 1x to 4x, it scales in steps (1x → 2x → 4x), applying sharpening between each pass. This stepped approach reduces the softness that comes from large single-step interpolation.

An optional unsharp mask is applied after upscaling to restore edge definition. Unsharp masking works by detecting edges (areas of high contrast) and increasing the contrast at those boundaries. This makes text, lines, and object edges appear crisper without affecting smooth gradient areas.

Bicubic upscaling works best on clean source material: screenshots, line art, logos, diagrams, and graphics with solid colors and sharp edges. Photographs benefit less because the interpolation cannot invent texture detail — a blurry 200x200 photo will become a larger but still blurry 800x800 photo. For photographic upscaling with detail synthesis, dedicated AI super-resolution models are needed.

Common use cases

• Preparing low-res images for print: Upscale web-resolution images (72 DPI) to print-suitable dimensions (300 DPI) when the original high-resolution source is unavailable.
• Enlarging screenshots and diagrams: Scale up small screenshots, UI mockups, or technical diagrams for presentations and documentation where they need to fill larger display areas.
• Retina display preparation: Create 2x versions of standard-resolution assets for high-DPI displays when only 1x originals are available.
• Social media minimum dimensions: Upscale images that fall below platform minimum dimension requirements (e.g., Instagram's 1080px minimum) to meet upload specifications.

Technical details

Interpolation method

Multi-pass bicubic resampling. Each pass doubles dimensions using a 4x4 pixel neighborhood for smooth interpolation. Multiple passes reduce artifacts compared to a single large-factor resize.

Scale factors

2x, 3x, and 4x options. 2x doubles both width and height (4x total pixels). 3x triples dimensions (9x pixels). 4x quadruples dimensions (16x pixels).

Unsharp mask

Optional post-processing that enhances edge contrast. Applied after the final upscale pass to restore definition lost during interpolation. Configurable radius and amount.

Limitations

Cannot invent texture or detail not present in the source. Works best on clean graphics, screenshots, and line art. Photographs may appear soft at high scale factors.

How to upscale an image online

Increase image resolution 2x, 3x, or 4x and download the larger version.

1. Drop one or many images into the upscaler.
2. Pick the scale factor and output format.
3. Click upscale to render the larger version locally.
4. Download the result or grab a ZIP for the whole batch.

Frequently asked questions