Woooooooooooosh! That was the sound of everything that John just explained going STRAIGHT over tanya's head......
tan. (who is completely mind-boggled at this point...) ----- Original Message ----- From: "John Francis" <[EMAIL PROTECTED]> To: <[EMAIL PROTECTED]> Sent: Sunday, December 07, 2003 9:32 AM Subject: Re: JPEG to TIFF or PSD Conversion > > > > If the information is lost when creating a JPEG file, where does it come > > from when converting the JPEG to PSD or TIFF? Or is the "lost" > > information never retrieved, and only the file is decompressed less some > > information? > > Lost information is gone for ever. > > A very simple analogy: assume our image consists of one hundred red pixels. > We can either store this as a list of one hundred pixel values, or store a > count (100) and a single pixel value. Conversion back & forth between these > representations doesn't lose or gain information, but will result in very > different file sizes. > > Now let's assume that the original image still consists of one hundred pixels, > but instead of being all exactly the same colour they exhibit very subtle > variations. We could still decide to approximate them by one hundred pixels > of the same colour so that we could store them in the compressed count/value > format. This would result in a nice small file. Converting this to a non- > compressed representation would give us the full one hundred pixel values, > but they wouldn't be the varied colours of the original source image. > > >
