# Test Image Generator — Any Ratio, Size & Quality

> Generate test images at any aspect ratio, resolution, pattern, quality or exact file size.

A test image generator creates images at whatever aspect ratio, resolution, pattern and quality you need — 16:9, 1:1, 9:16, Open Graph 1.91:1 or a custom size — as PNG, BMP, GIF, JPEG or WebP. Use them to check responsive layouts, upload limits, thumbnail cropping and compression behaviour.

**URL:** https://convertto.tech/t/sample-image-generator
**Category:** Samples & Mock Data (https://convertto.tech/c/sample-data)
**Privacy:** Runs entirely in the browser; no upload
**Cost:** Free, no sign-up
**Last updated:** 2026-08-01

## Key facts

- **Ratios:** 11 presets from 1:1 to 21:9, plus A4 portrait and landscape and fully custom dimensions
- **Resolution:** Up to 12,000 px on the longest edge, capped at 40 megapixels
- **Patterns:** Solid, linear and radial gradients, checkerboard, grid, stripes, colour bars, mesh and noise
- **Exact sizing:** PNG output can be padded to a precise byte count via a metadata block
- **Privacy:** Runs entirely in your browser — nothing is uploaded
- **Cost:** Free, unlimited, no sign-up

## How to use

1. Choose the aspect ratio.
2. Set the longest edge.
3. Set the width.
4. Set the height.
5. Choose the pattern.
6. Pick the primary colour.
7. Pick the secondary colour.
8. Set the pattern scale.
9. Choose the format.
10. Set the quality.
11. Turn "Pad to an exact file size" on or off as needed.
12. Set the target file size.
13. Choose the unit.
14. Set the how many images.
15. Enter or paste your seed.
16. Press Run, then download the result when it is ready.

## FAQ

### Why would I want noise instead of a gradient?

Noise is effectively incompressible, so it is the worst case for a compression or bandwidth test. A gradient compresses extremely well and gives you the opposite extreme with the same dimensions.

### How do I get a file of an exact size?

Choose PNG and enable "Pad to an exact file size". The generator appends a metadata block sized to make up the difference, which leaves the image itself untouched.

### What are the colour bars for?

They are a test card. Because the eight bars have known values, they make it obvious at a glance if a pipeline has shifted colours, swapped channels or clipped the range.

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- [Sample File Library](https://convertto.tech/t/sample-file-library): Download a ready-made ladder of 15 sample files: size steps, page counts, aspect ratios, durations or row counts.
- [PDF to BMP Converter](https://convertto.tech/t/pdf-to-bmp): Convert PDF pages into uncompressed 24-bit BMP bitmaps.
- [What Is My Screen Resolution?](https://convertto.tech/t/screen-resolution-checker): Check your screen resolution, browser viewport, device pixel ratio, colour depth and GPU.