![]() With PNG, we haven't lost any detail in our images, we've just made them smaller. JPEG is lossy, so as file sizes decrease, more and more of the image is lost. I know it doesn't sound like much, but PNG is by definition lossless compression. But even without interlacing, PNGOUT reduces the file size by 22 KB, or nearly 10 percent. If you have interlaced PNG images, you can expect a very substantial reduction in file size. If we run Ken Silverman's PNGOUT* on the files, we can crunch them down even smaller: PNG, interlaced 190 KBįirst, note that PNGOUT strips out any interlacing. It's a testament to the efficiency of the PNG image format. They render in obvious and simple fashion, from top to bottom.Ģ12 KB is an impressively small filesize for such a large and detailed image. Standard PNGs have a perfectly acceptable progressive rendering solution without interlacing.As Philip Greenspun so aptly pointed out, readers can't tell when an image is "done". Progressive rendering is confusing the image gets less and less blurry over time.Interlaced PNGs are 35% larger for the single purpose of progressive rendering.So here's our first lesson: never save interlaced PNG files. When I save this file directly from Paint Shop Pro as a 24-bit PNG file, I get the following file sizes: PNG, interlaced 288 KB The actual size of the screenshot is 1233 x 946. We want nice, crisp transitions between the white and dark areas of the screenshot. It's a perfect candidate for the lossless PNG file format, because there are large areas of the same colors and hard transitions between them. ClearType font rendering is on, and there's a nice mix of text, graphics, and UI. I took a quick screenshot of this website, along with all the browser chrome, transparency, and shadows. But as great as PNG is, there are a few things you should know about PNG to get the most out of it. It's copyright-free, it can store all bit depths, it can represent alpha channels, and it offers more efficient compression. In every other way, PNG is the natural heir to GIF. In my experience, GIF filesizes are smaller in this scenario. Your image is extremely small, on the order of a few hundred bytes.You should always choose PNG over GIF, except in the following two circumstances: PNG is a more modern and vastly improved version of GIF that (almost) completely obsoletes it. But the choice between GIF and PNG is no contest. See my comparison of GIF/PNG and JPEG if you're not clear on what the difference is. Deciding which image format to use is relatively straightforward you choose lossy JPEG when you're saving continuous-tone photographic images, and you choose between lossless GIF or lossless PNG when you're saving images with large blocks of the same or similar colors. When it comes to image formats on the internet, it's generally a three-way tie between JPEG, GIF, and PNG.
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