Unit 25 ,task 4 , D2

D2

 How to save guide.

There are two kinds of image compression, lossy and lossless.

• Lossy compression is when you Decompress , compressed data that will not have the exact same properties as the original , although this will only be visible at a closer look.  

•  When decompressing a lossless image you will end up with the exact same image although this compression uses more memory which isn't really efficient enough to be on the web.

Internet Graphics:

JPEG is a lossy image type and you can control the compression level in image editors. This is good for saving images like photographs , drawings with different shades and images that contain gradients with millions of colours as it compresses them down to smaller sizes , sufficient enough to still look appealing and visible. Overall it is good for the web as it uses a small amount of memory although sufficiently similar to the original image. Due to all of this ,saving in this file format for internet graphics will be the best choice. The image below shows the same picture in the format of JPEG , with different qualities. It's visible that there is a slight change in resolution and sharpness but it is still usable within the web, this also means the higher quality the longer it takes to download which would mean it would be better to pick an average quality. There is also another format which is widely supported and that is the GIF image format ,this being supported by nearly every web format.

Large Format Graphics:

For large format graphics the PSB format would be best as it is a file extension for an image file used in Photoshop , these is a large document format and is similar to a PSD but can hold a larger image size. This supports large graphic formats as it can save an image size from 300,000 to 300,000 pixels.You can also save high dynamic range, 32‑bits-per-channel images as PSB files. Although the PSB format would be desirable to use the PSD format can also be saved as a TIFF which converts it into a file format that is compatible with a wider range of software than the PSB. This being useful as it enables the user to save the image in a more efficient way which will work best with the software they will be using. However , overall the PSB would be the best choice as size is the main concern , it will save the image in high quality within the terms of resolution and colour depth better than the JPEG format as the pixels in the image wont be exposed.

Leaflet suitable graphics:

 Like GIFs, PNG file formats support transparency, although PNG supports variable transparency, this means that the user of the software can change the settings of transparency of the image. This is a positive aspect but older versions of software or less compatible software wont show the transparency settings in the same way , thus meaning it could be ineffective and unattractive to the eye. This file format is downloadable twice as fast as GIF images as they have two dimensional interlacing. JPEG format can also be used as it is the sort of image compression that works well with complex images , it decreases the files size by removing colours that aren't visible to us , there is a downside to this because if important colour image information is lost it wont be recovered unlike the PNG format. JPEG can also be loaded in stages which slows down the time taken to download.