How to use the halftone converter
- Choose or drop an image. A sample appears without one.
- Set the layout (grid or hexagonal), cell size, dot size, grid angle and color, and the preview changes at once.
- Press "Save PNG" or "Save SVG". Use SVG when you need to enlarge it, such as for print, and PNG to use on the web straight away.
Halftone in digital images and the visual principle of pointillism
Beyond a certain distance, the human eye cannot tell very small dots apart and takes in the average brightness of the area they form. Halftone uses this property. Even with a single black ink, changing the size of the dots makes an area look darker or lighter, which made it the method for printing photographs with continuous tones. Large, closely packed dots go in dark areas and small, sparse dots go in bright areas.
Developed for printing photographs in 19th-century newspapers, the technique is still used today. Typical layouts are dots on a regular grid and a hexagonal arrangement where every other row is shifted by half a cell. In art, pointillism uses a similar principle: placing dots of color side by side makes the colors blend in the eye. Choosing original colors in this tool paints each dot with the average color at its place for a similar effect.
How the conversion works and uses
The process is simple. The image is divided into cells at regular spacing, the average brightness of each cell is found, and a larger dot is drawn the darker it is. The radius is set to the square root of darkness so that the dot area is proportional to the brightness. Tilting the grid reduces the artificial look of dots lined up in rows. Smaller cells are finer, and larger cells give a coarse pop-art feel.
The result is used for merchandise and posters, T-shirt designs, social media profile images and retro-style backgrounds. Saved as SVG, the dots are vectors, so it stays sharp even printed large and the dot colors can be changed in an editing program. Note that when there are tens of thousands of dots, the file gets large and some programs open it slowly, so enlarge the cell size to reduce the number of dots.
Tips for good conversions
- Photos with clear contrast and a simple subject suit it well.
- Choose a cell size so the dots are visible at the final size.
- If dots overlap too much, reduce the dot size.
- For photos with a dark background, try Invert.
- For print, save as SVG so it stays sharp when enlarged.
FAQ
What is halftone?
Halftone is a printing technique that expresses light and dark with only one ink color by using small dots of different sizes. Large dots in dark areas and small dots in bright areas blend from a distance into an in-between tone. It is the texture you see in newspapers, comics and pop art.
Should I save SVG or PNG?
A PNG is an image of a fixed size, while an SVG is a vector file recording the position and size of each dot, so it stays sharp however much you enlarge it. SVG is good for print and large output, and PNG is handy for posting straight to the web or social media. With very many dots the SVG gets large.
Why is 45 degrees the default angle?
At 0 degrees, where dots align horizontally and vertically, they look like rows, seem artificial and easily cause moiré. In printing the grid is tilted to be less noticeable, and 45 degrees is the most common for black-and-white halftone. Try anything from 0 to 90 degrees to suit your taste.
Notes & limitations
This tool visualizes an image as a dot pattern. Images are processed only in the browser and not sent to a server. When publishing or selling conversions of other people's photos or works, check copyright and portrait rights.