Image Opacity
Make an entire image partly transparent by setting its opacity from 0 to 100 percent. Images without transparency get an alpha channel first, and images that already have one keep their shape while every alpha value is scaled, so soft edges and cutouts stay intact. Ideal for watermarks, overlays, faded backgrounds, ghosted UI states and layered designs.
Frequently asked questions
How does the opacity setting work?
The opacity is a percentage that multiplies the alpha value of every pixel. At 100 the image is unchanged, at 50 it is half transparent and at 0 it is completely invisible. Decimal values are accepted.
What happens to a JPEG without transparency?
An alpha channel is added first with every pixel fully opaque, and then the opacity is applied. A JPEG at 50 percent therefore becomes a PNG where every pixel is half transparent. The colors stay the same.
What happens to images that already have transparency?
Existing alpha values are scaled rather than replaced. Fully transparent areas stay transparent, and a pixel that was 80 percent opaque becomes 40 percent opaque at an opacity of 50. Cutouts and soft shadows keep their shape.
Why is the result a PNG?
JPEG cannot store transparency, so the result is saved as a PNG with an alpha channel. Grayscale images keep their gray tones and gain the alpha channel. You can convert the file to WebP or AVIF afterwards if you need a smaller transparent file.
What opacity is good for a watermark?
Logos used as watermarks typically look best between 20 and 40 percent, visible enough to identify ownership without hiding the photo. Use a logo with a transparent background so only the mark itself is faded.
Will the image look faded when I open it?
In browsers and design tools it appears semi transparent over whatever is behind it, often a checkerboard or white page. Some simple image viewers show transparent pixels as black, which can make it look darker than intended.
Can I make an image fully transparent?
Yes, an opacity of 0 sets every alpha value to 0. The colors remain stored in the file but are invisible. This can be useful for placeholders that must keep their dimensions.
Which formats can I upload?
JPEG, PNG, GIF, WebP, TIFF and AVIF images up to 5 MB are supported. Animated files use their first frame and images over 4000 pixels on a side are scaled down to fit.
Does changing opacity alter the colors?
No, only the alpha channel changes and the red, green and blue values are kept exactly. The visual change comes from what shows through behind the image.
What engine is used?
The tool uses the ensureAlpha and linear operations of the sharp library to add and scale the alpha channel. The result is exact and repeatable.