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View Full Version : 24 vs 48 bit Color Scans



Leighgion
08-08-2006, 07:44 PM
I've got a shiny new/refurbed Epson 4870 scanner. It slices, it dices, it scans both reflectives and transparents. Going a bit wild on my first scans of some of my sister's old 35mm negatives, I selected 2400dpi with 48bit color. However, I've run smack into the unforeseen problem that Photoshop Elements 3 has very limited support for 8 bits per channel. Many tools and filters simply don't work. Guess it's an incentive to upgrade to CS2, but I'm not really a heavy enough image jockey to justify that expense.

My question to those who might know is, am I totally going overboard by scanning 48bit? My sister was a prolific amateur photographer once upon time with a decent SLR, so I want to treat her stuff well, but we were not a rich family so this film is by no means really high end. If I'm just wasting bytes and 24bit is enough, please let me know.

Nicolas
08-09-2006, 02:32 AM
You can compare the Bitrate to the audio Bitrate.
Twice the data more samples will be made.

48 Bit is good if you want to replace color cuz due to the higher sampling the color will not cut up as much as in 24 Bit.

48Bit = 16Bit per Channel (RGB = 3x 16Bit)
PS CS2 can work with those images older versions of PS are cut down in function in 16Bit mode.

The main point is all images will be printed in CMYK (if ya dont print on Theramlsub. printers/Halftone) which is 4x 8Bit (8Bit = 256 steps in between lightest and darkest point). So thats just 36Bit.

If ya convert images from RGB 48Bit to CMYK 36Bit you'll get a greater colorspace and you lose less details. Thats why I am explaining dont convert CMYK images to RGB (8Bit) you'll lose details.

Most scanner softwares are doing image manipulations in 48Bit cuz you can "stretch" colors more than in PS 24Bit. Before PS CS/2 this was the only way if you have to "bend" colors extremely.

Regards

Nicolas