Scanner Resolution Advice Please?

  Tinkey Winkey 09:50 02 Apr 2007


Have just bought the Epson RX560 all-in-one printer & scanner, but didn't realise there was higher model- the RX640 !
(I'm starting to get that Homer Simpson feeling.Doh!)

RX560 scanner = 1200 x 2400 dpi 48 bit
RX640 scanner = 6400 x 3200 dpi 24 bit

I don't understand what these specs mean could someone briefly & simply explain please?

I want to scan & copy photos up to A4 size mostly.
I may occasionally print one or two on my old A3 printer aswell.

Am I really likely to notice much, if any difference between these scanners please?

Should I return the it and get the RX640 instead?

  Gongoozler 09:59 02 Apr 2007

Hi Tinkey Winkey. 48bit scans will give you finer gradation of colour shades. The dpi rating defines how much fine detail the scanner can resolve. What you also need to take into consideration is what the OPTICAL resolution is. The published resolution is often obtained by interpolation, i.e. the scanner electronically calculates the points between those it actually samples. The A$ scans should be no problem. When finer resolution helps is when you scan a small image and then stretch it, very much like using electronic zoom in a digital camera. For 1:1 scanning you are unlikely to want to scan at anything greater than 300, or possibly 600 dpi. Greater than that is likely to result in a HUGE file size. Most printers will only give you 300dpi anyway.

  Tinkey Winkey 10:15 02 Apr 2007

Thanks Gongoozler,
(Please note my original posting should read:)

RX560 scanner = 1200 x 2400 dpi 24 bit
RX640 scanner = 6400 x 3200 dpi 48 bit

(Got the 24 & 48 bit specs the wrong way round Doh!)

Yes, I set the optical resolution to 600dpi.

As I haven't seen scans taken using 48bit 6400 x 3200 I can't compare the results?
If anyone has used both I'd be interested to know your opinions in differences?

Should I get the RX640 with higher scanner res & dpi instead, or is the RX560 good enough?

  Gongoozler 11:38 02 Apr 2007

Tinkey Winkey, what do you want to use the pictures for? For most applications I think that 1200 x 2400 dpi 24 bit will be adequate. If you really want the ultimate in print quality you will need to spend hundreds of pounds. I use the Epson 3490 photo scanner click here and am very pleased with the results. It's a 48 bit scanner, and I rarely use more than 600dpi because it slows the scanner right down and the output file becomes so large. A simple calculation of this is to look at the number of dots in the picture (e.g. an 8inch x 4 inch picture at 600 dots per inch would be 8 x 600 x 4 x 600 dots = 11,520,000 dots, each dot is 48 bits = 552,960,000 bits or about 69M Bytes). Just as well that we have JPEG compression!

  Fingees 11:56 02 Apr 2007

When using it, be careful when copying, as sometimes too high resolution makes the picture look far grainier than they relly are.

So don't overdo thr resolution.

All the best.

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