Transparent backgrounds: what the file stores, and why it sometimes turns black

Why did my transparent PNG land on a black box?

You export a logo with no background, upload it to your Etsy shop, and it shows up sitting on a black rectangle. Nothing is wrong with the file. Etsy's help page spells it out: transparent PNGs aren't supported there, and whatever was transparent shows up black.

The same thing happens whenever an image with transparency is pushed somewhere that can't hold it. JPG is the usual suspect. It has no alpha channel, so whatever writes the JPG has to flatten the picture onto a solid color first, and every program picks its own:

• Web browsers: the HTML Standard tells them to composite onto opaque black when a canvas is exported to a format without alpha. A tool that exports through the canvas without painting a background first ends up with black.
• Photoshop Elements: Save for Web fills with white when no matte color is picked for a JPEG.
• LivreImage: paints the canvas white (#FFFFFF) before writing a JPG, PDF or BMP.

Pasting is the least predictable route: it depends on what the source app puts on the clipboard and what the receiving app can read. If a pasted cutout arrives on black or white, try inserting the saved file instead.

What the alpha channel actually stores

Next to red, green and blue, each pixel carries a fourth value, the alpha, that says how opaque it is. In the PNG specification an alpha of zero is fully transparent and the maximum (255 in an 8-bit channel) is fully opaque; everything in between is a partially transparent pixel. A red pixel with an alpha of 128 shows about half red and half whatever sits behind it.

Two details from that spec explain most surprises. First, the file defines the foreground and its transparency mask, but not the background; whatever displays the image supplies one. Second, a transparent pixel still has a color stored underneath. The spec expects that some readers won't fully support transparency, which is why it advises giving transparent pixels a reasonable background color. In a browser canvas the default empty pixel is transparent black (0, 0, 0, 0). Drop the alpha and black is what's left.

Which formats keep transparency, and which can't

Soft edges and fading shadows need partial transparency. Not every format gets that far.

GIF's on-or-off rule is why old logos and stickers have jagged rims. Per the GIMP manual, semi-transparent edge pixels are forced to fully visible or fully invisible, and the anti-aliasing is lost.

The halo around a cutout is leftover background

In the original photo, edge pixels are already a blend: part jacket, part sky. A cutout gives those pixels partial alpha, but the blended color stays. Adobe's Photoshop help describes the same effect: partially transparent edge pixels keep color from the original background, and it shows once the selection moves somewhere new.

Put numbers on it. A red jacket (200, 30, 40) against blue sky (90, 150, 230) makes an edge pixel of (145, 90, 135). At 50% alpha over white it displays as (200, 172, 195), a lilac tint that was never in the jacket. A quarter of the sky is still in that pixel.

LivreImage's background remover doesn't repaint edge colors: each pixel keeps its photo color and takes its alpha from the AI mask. Your lever is the Cutout level slider. Drag it right and the uncertain band gets more transparent, so the halo shrinks. Do it before downloading; once a new background is flattened in, edge and halo are the same pixels.

What transparency costs in file size

What editors label PNG-24 with transparency is, in the spec, truecolor with alpha: four 8-bit samples, 4 bytes per pixel. A 2,000 × 2,000 px image is 16,000,000 bytes before compression. A palette PNG (PNG-8) stores a 1-byte index per pixel instead: 4,000,000 bytes, plus a palette of up to 256 colors and its alpha table.

The catch with PNG-8 is that 256-color ceiling: fine for a logo or an icon, while a photo has to drop tones to fit. One more trap: the spec allows partial alpha for every palette entry, yet Adobe's Photoshop Elements help describes PNG-8 as one-level transparency, like GIF. What you get depends on the exporter.

WebP is the shortcut. Google reports lossless WebP files 26% smaller than PNG, and says lossy WebP, which also carries alpha, is typically 3 times smaller than PNG. In its study of 12,000 PNGs crawled from the web, lossless WebP compressed 23% better than PNGs already optimized with ZopfliPNG.

LivreImage writes PNG through the browser's encoder: lossless, with no reduced-palette option. To cut weight and keep the alpha, use PNG to WebP or lower the pixel dimensions.

Where to flatten before you upload: marketplaces, email, print

Transparency only works when the destination knows what to put behind the image. These three often don't.

Email

The background belongs to the reader's mail app. In dark mode, Outlook swaps the white message background for black, so a transparent logo with dark lettering can vanish. WebP is risky too: the Can I email tables list it as not supported in Outlook for Windows (2007 to 2019) and as converted to JPG by Gmail, while PNG has no unsupported entry at all.

Print

Adobe notes that artwork with transparency usually has to be flattened on its way to print. Garment printing is the reverse case: Printful suggests a PNG with a transparent background, yet warns that semi-transparent pixels print poorly and let the white base show through. The soft edge of a cutout is made of exactly those pixels.

Marketplace rules change. Before redoing a whole catalog, open the official page listed under Sources.

How LivreImage handles transparency, tool by tool

The general rule, in tools that run in your browser: formats with alpha keep the transparency, formats without it get white.

Two exceptions

• The compress-to-a-target pages (100 KB, 200 KB and the rest) open on JPG: switch the format to WebP before generating if the background has to stay transparent.
• A format your browser can't write gets a stand-in. Without WebP, the output falls back to PNG and the transparency survives. AVIF is not written by LivreImage today: the option only appears when the browser reports that it can encode the format, and in our tests of September 2026 Chrome could not.