Large image files supported
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Image converters / emmulator for typical 80 and 90 technology in your browser, note big images might make them slow depending upon your hardware. I will try to care about your attention
Patterns of pixels to create an optical illusion
Dithering is crucial for low-resolution and limited-color printing because it enables the reproduction of continuous-tone images (like photographs) using only a binary (black-and-white) or very limited color palette. By using a carefully arranged pattern of dots (dithering algorithm), dithering tricks the human eye into perceiving shades of gray and smoother gradients that the printer or display can not produce.
The printer has no grey ink. It can only fire a pin or not fire it — a dot exists or it doesn't. But your eye blends nearby dots together when you view them from a distance. So if half the dots in an area are fired and half aren't, your eye perceives it as 50% grey. If 20% fire, it looks light grey. If 80% fire, dark grey.
The problem: if you just say "fire a dot wherever the pixel is darker than 128", you get a hard cut — everything above the threshold is white, everything below is black. No grey at all. That's what "None (Threshold)" does.
Dithering solves this by distributing the error from rounding each pixel to the next pixels, so the overall average brightness stays correct. The four algorithms differ in how they spread that error:
In these converter you will usally find 4 Dithering alternatives:When a pixel gets rounded (say a 90-brightness pixel becomes white/255), the error (90-255 = -165) gets pushed to the right neighbour and the row below in specific proportions (7/16, 3/16, 5/16, 1/16). The neighbours then remember they're owed some darkness, so they're more likely to become black. This produces organic, flowing dot patterns that follow the image contours. Best overall quality.
Similar to Floyd-Steinberg but only propagates 3/4 of the error instead of all of it. The remaining error gets discarded. This means bright highlights stay very clean and white, but very dark shadows can lose detail. Looks slightly lighter and crisper than Floyd-Steinberg. The algorithm was developed at Apple for the original Mac.
No error diffusion at all. Instead it compares each pixel against a fixed 4×4 grid of threshold values. The same grid repeats across the whole image, so you get a regular geometric dot pattern — a visible crosshatch texture that looks very mechanical and "printed". This is the most authentically computer-era looking result.
Pure cutoff. Below threshold = black dot, above = nothing. Produces harsh posterised output with no grey at all. Only useful if you want a high-contrast graphic look.
In colour mode the same principle applies but for ink coverage — pixels with low colour saturation get fewer coloured dots, highly saturated pixels get more, and the dither algorithm decides which individual pixels get a dot to hit the right average.
