#How to compress picture for website software#
#How to compress picture for website download#

Using this information to your advantage the compressor can apply delta encoding where instead of storing the individual values for each pixel, you can store the difference between nearby pixels: if the adjacent pixels are the same, then the delta is 'zero' and you only need to store a single bit! But why stop thereвЂ¦ Next, once you've optimized the data stored in individual pixels you could get more clever and look at nearby pixels as well: turns out, many images, and especially photos, have many nearby pixels with similar colors- for example, the sky, repeating textures, and so on. On the other hand, if the image only uses a few colors, then a large palette is simply wasting precious bits! What if you reduce the palette to 256 colors? Then you would only need 8 bits in total for the RGB channels and immediately save two bytes per pixel-that's 50% compression savings over the original 4 bytes per pixel format! Left to right (PNG): 32-bit (16M colors), 7-bit (128 colors), 5-bit (32 colors).Д¬omplex scenes with gradual color transitions (for example, gradients or sky) require larger color palettes to avoid visual artifacts such as the pixelated sky in the 5-bit asset. One simple strategy is to reduce the 'bit-depth' of the image from 8 bits per channel to a smaller color palette: 8 bits per channel gives us 256 values per channel and 16,777,216 (256 ^ 3) colors in total. Thankfully, a lot can be done to reduce the image file size. This post has so far only focused on the 'uncompressed' image format.

100x100 pixel image is composed of 10,000 pixelsДimensions Pixels File size 100 x 100 10,000 39 KB 200 x 200 40,000 156 KB 300 x 300 90,000 351 KB 500 x 500 250,000 977 KB 800 x 800 640,000 2500 KBДЈ9В KB for a 100x100 pixel image may not seem like a big deal, but the filesize quickly explodes for larger images and makes image assets both slow and expensive to download.

As a result, if we know the dimensions of the grid we can easily calculate the filesize: Internally, the browser allocates 256 values (shades) for each channel, which translates to 8 bits per channel (2 ^ 8 = 256), and 4 bytes per pixel (4 channels x 8 bits = 32 bits = 4 bytes).

In turn, each pixel stores the ' RGBA' values: (R) red channel, (G) green channel, (B) blue channel, and (A) alpha (transparency) channel.

Д«ecause SVG is an XML-based format, you can also apply GZIP compression to reduce its transfer size-make sure your server is configured to compress SVG assets!ДЄ raster image is simply a two-dimensional grid of individual 'pixels'-for example, a 100x100 pixel image is a sequence of 10,000 pixels. As a result, it is always a good idea to minify your SVG files by running through a tool like SVGO.Д¬ase in point, SVGO reduces the size of the above SVG file generated by Illustrator by 58%, taking it from 470 to 199 bytes. The above example renders the below simple circle shape with a black outline and red background and was exported from Adobe Illustrator.ДЄs you can tell, it contains a lot of metadata, such as layer information, comments, and XML namespaces that are often unnecessary to render the asset in the browser.

#How to compress picture for website software#

Most vector-based drawing software can create SVG files or you can write them by hand directly in your favorite text editor. You can embed the SVG markup directly on the page or as an external resource. Optimizing vector images #ДЄll modern browsers support Scalable Vector Graphics (SVG), which is an XML-based image format for two-dimensional graphics. Finding the optimal settings for your image requires careful analysis along many dimensions: format capabilities, content of encoded data, quality, pixel dimensions, and more. Image optimization is both an art and science: an art because there is no one definitive answer for how best to compress an individual image, and a science because there are many well developed techniques and algorithms that can significantly reduce the size of an image.

#How to compress picture for website download#

As a result, optimizing images can often yield some of the largest byte savings and performance improvements for your website: the fewer bytes the browser has to download, the less competition there is for the client's bandwidth and the faster the browser can download and render useful content on the screen. Images often account for most of the downloaded bytes on a web page and also often occupy a significant amount of visual space.

Lossless versus lossy image compression.