About PNG (Portable Network Graphics)
If you are saving a screenshot, a logo, a chart, or anything with sharp edges and flat colors, PNG is usually the right answer. It compresses without losing a single pixel of information, so text stays crisp and colors stay exact no matter how many times the file is opened and re-saved.
PNG (Portable Network Graphics) was created in 1996 as a patent-free replacement for GIF and has been a web standard ever since. It added two things GIF never had: full 24-bit color and an 8-bit alpha channel — smooth, partial transparency — which is why PNG became the default for logos and interface graphics layered over other content.
Its weakness is photographs. Because PNG refuses to throw any data away, a photo saved as PNG can be five to ten times larger than a good JPEG with no visible benefit. Convertmaxxing converts PNG to and from JPG, WebP, AVIF, and more, entirely in your browser — nothing is uploaded, and it is free.
Strengths
- Completely lossless — pixels survive unlimited re-saves exactly as they were
- Full alpha-channel transparency, essential for logos and overlays
- Universal support across browsers, editors, and operating systems
- Ideal for screenshots, text, line art, and flat-color graphics
Limitations
- Large files for photographs — often several times the size of a JPEG
- No lossy mode, so you cannot trade a little quality for a much smaller file
- No practical animation support — APNG exists but is rarely used
Why PNG is tiny for graphics and enormous for photos
PNG compresses in two stages. First it applies a per-row filter that rewrites each pixel as the difference from its neighbour above or to the left. On a flat-colour graphic, that turns a long run of identical pixels into a long run of zeros. The filtered result then goes through DEFLATE, the same general-purpose compression used inside ZIP files, which is exceptionally good at squeezing runs of repeated values.
That pipeline explains both of PNG’s personalities. A screenshot of a text document is mostly flat regions and repeated patterns, so the filters produce mountains of zeros and the file comes out remarkably small. A photograph has no repeated values anywhere — every pixel differs slightly from its neighbours because of sensor noise and natural texture — so the filters produce noise, DEFLATE finds little to work with, and the result is several times larger than a JPEG that looks identical to the eye.
PNG-8, PNG-24, and what the alpha channel buys you
What people call PNG-24 is the full-colour variant: up to 16.7 million colours plus a separate 8-bit alpha channel giving 256 levels of partial transparency. That alpha channel is why a PNG logo can have genuinely soft anti-aliased edges that composite correctly over any background colour, instead of the jagged fringe you get from formats offering only fully-on or fully-off transparency.
PNG-8 is the palette variant, limited to 256 colours chosen for the specific image. For flat graphics, icons, and simple illustrations it can be dramatically smaller than PNG-24 with no visible difference, because those images never contained more than a couple of hundred distinct colours to begin with. It is a poor fit for anything with gradients or photographic content, where reducing to 256 colours produces visible banding across smooth areas.
Frequently asked questions
- Why is my PNG file so large?
- Almost always because it contains a photograph rather than a graphic. PNG stores every pixel exactly, and photographs have no repeating patterns for its compression to exploit. A 12-megapixel photo can easily be 20 MB as a PNG and under 3 MB as a high-quality JPEG that looks the same. If the image is a photo and does not need transparency, converting to JPEG or WebP is the fix.
- Does converting PNG to JPG lose quality?
- Yes, once. JPEG is lossy, so the conversion discards some detail — though at quality 85 or above that loss is hard to see in a photograph. The bigger issue for graphics is artifacting: text and sharp lines pick up visible halos and smudging that the PNG did not have. The loss is also one-way, so converting the JPEG back to PNG will not bring the detail back.
- Will converting to PNG make a blurry or artifacted image sharp again?
- No. Converting to a lossless format preserves exactly the pixels it is given, including blur and compression artifacts already present. PNG stops further degradation from accumulating, which is genuinely useful before a round of editing, but it cannot reconstruct detail an earlier lossy save discarded.
- Does PNG support animation?
- There is an extension called APNG that adds animation, and modern browsers do display it, but support outside the browser is patchy and most tools ignore it. In practice PNG is a still-image format, and Convertmaxxing converts still images only.