Vignette Image

Vignette effect darkens pixels by their distance from the center. Strength opens at 55 percent. A white corner becomes 115. The center of white stays 255.

Fifty-five percent on white

The slider is labeled Vignette strength % and runs from 10 to 100 in steps of 1. It opens at 55. Strength is that percent divided by 100, then clamped between 0.1 and 1. For each pixel, distance from the center is divided by the distance to the corner. The factor is 1 minus that distance raised to 1.6, times the strength. Red, green, and blue are multiplied by the factor and rounded. Alpha is left as it was. On a 100 by 50 picture the center pixel has distance 0, so white stays 255. A corner pixel at 55 percent has factor 0.45 and white becomes 115. At 100 percent the same corner becomes 0. The canvas width and height do not change.

What the darkening does not do

There is no color for the vignette. Edges move toward black, not toward a chosen hue. There is no separate control for the radius. The falloff exponent is fixed at 1.6. A JPEG is saved as PNG. The file name ends with vignette-image.png, using the original name with the extension removed, or the word image when the name is missing. Download PNG is the button. With no picture loaded, the message is Please upload an image. The inner picture is not scaled. Transparent pixels keep their alpha, and the color channels still get the factor. There is no blur mixed into this pass.

How to check the corner

Upload a flat white picture and leave the slider at 55. A pixel in the middle should still be 255, 255, 255. A corner pixel should be about 115 on each color channel. Move the slider to 100 and the corner should fall to 0 while the center stays white. The width and height of the download should match the source. If the canvas grew, the file did not come from this slider. If the edge is blue or another hue, a different effect ran. The download is PNG even when the source was JPEG. Keep the source if you still need the original file.

The picture stays in this tab

The darkening runs in this browser. The picture is not uploaded. Download PNG uses the strength that is on the slider at that moment. Closing the tab drops the preview. The next visit does not keep that picture. Strength 55 is the opening value. Strength 10 is the lowest the slider allows. Strength 100 pushes a corner of white to 0. The center is unchanged because its distance is 0. Alpha is copied through. The saved name ends in vignette-image.png. A JPEG source is still a PNG download.