elements tiff problem

[stevefranc]

I am new to photoshop and digital imaging. I have an epson 4990 scanner, while scanning negatives at 4800dpi,the tiff file saved to my desktop is about 50mb from a 35mm neg. But when I make small changes in elements then save to desktop as a tiff again, my file seems to be 25mb. Where has 25mb of info gone?Im very confused, I understand saving as a jpeg would diminish the size but why as a tiff

[Chuck S.]

Steve, what are the pixel dimensions of the image when opened (Image>Resize>Image Size)?

[Ric Cisson]

Steve, in the image type box of your scanner driver window, are you scanning at 48 bit or 16 bit?

[stevefranc]

16 bit greyscale

[Chuck S.]

Pixel dimensions?

[Ric Cisson]

Steve, when I scan my B&W on my 4990, I scan in 48 bit per channel (color) @ 4800 DPI. Anytime you take a file into Photoshop Elements to manipulate from your scan, PSE converts to a workable bit depth. Usually that is either 16 or 8. Since most of the manipulations in PSE occur at 8 bits, I suspect that is what you are experiencing. So the program is actually "dispensing" as it were, itself of data as it "compresses" that data into the space you are working, in this case the color. I don't know all the technicalities and maybe I have the wrong terminology in place here for you, but in a nutshell that is what is happening. So for example, let's say I scan a B&W 35mm neg at 48 Bits per Color Channel @ 4800 Dpi. My scanned file is somewhere around 150 MB in size. But because Elements is optimized for working in 8 Bit the file has to be converted through the programs technical wizardry to 8 bit. In the end I still have much of the information in tack, however my file has been reduced to usually around 74 or 75 MB for B&W @ 8 bits per channel. Don't know that this helps you, but I think that is your answer for what you are experiencing. It is not compressing the tif file, it is converting the way the bit information is stored for your use in PSE.