----- Original Message ----- From: "Emily L. Ferguson" : C'mon, Jeff. it's not getting transformed. it's getting un-jpegged, : which reveals its true size. Emily (no attack, be assured of that), there is no such thing as unjpegging, what you are doing is converting the image to a different file *type* and adding data by changing the bitdepth - mind you this data is just extra numbers and not actual picture information. a bit like we write $5 shorthand when we might instead write $5.000000 - there's no further information, and certainly no more money.. but it tends to bloat a written page quickly if we do this hundreds of numbers :-) another example. Take a gif with a bit depth of 2 colours - black and white, but make it just white then save it as a TIF I just made a white 2 bit image - 842 x 1191 Pixels it's: 1.69Kb as a GIF As a jpeg (uncompressed, 100% quality) it's 6.33Kb interestingly at it's LOWEST quality jpeg setting it's still 6.33Kb ( I guess the jpeg compression format is clever enough to know what white is white and at 100% quality it needs little information ;-) as a bitmap or a tif it's 125kb there's no more information stored, just an inefficient file storage type (for this image) and a much greater bit depth is being recorded : The file is 2.2M when uncompressed. actually, when it's converted to a high bit depth file type it's 2.2M. If we tomorrow had a 64 bit image storage format we could also save it in this format and subsequent bit depth and the image would blow out to 32Mb - we'd still have no more actual picture information, nor would we see any more colours, but we WOULD be recording the image in a larger bit depth. most of : us are opening it in software which uncompresses it and reveals how : many pixels it has and at what density. yes we are - I certainly would not open an image in a program that automatically drops bit depth.. but then neither would I use a program that adds bit depth! ;) : I'll bet everyone is getting the exact same statistics I'm getting : when they do what I've been doing. not quite.. k
