Flatbed resolution: optical vs. interpolated

The tech specs say the scanner has 2400x4800 optical resolution. So

2400 dpi scans are the limit without interpolation. What about 4800?

Does scanning at this resolution add real data to the image or is the

outcome the same as if the image was resampled at a higher resolution

in Photoshop?

Experiment with it. In fact all the scanner is doing is stepping at half pixel intervals, so instead of 2400dpi, you get 4800. However, since the scan head is only 2400ppi, the scanner interpolates the rest of the data. It most likely will not (and im my experience it doesn't) produce a higher quality image. You will most likely do better scanning at 2400dpi and interpolating in photoshops bicubic, with Stair Interpolation, or with Genuine Fractals.

I did tests with a number of different films (chrome, color negative, black and

white negative, even Agfa Scala black and white positive) and looked at the

results both on screen and in prints from an Epson printer. I could se no

difference at all between 2400 and 4800. It just makes your file 4 times

larger.

My experience it that this scanner only does a true, hardware 1800-2000 dpi in the first place.

I will say that in my tests the Epson does better at 2400dpi. Niether the 4800 mode on the Epson or the bicunic in PS 6 does it justice when compared to a 4000dpi scan. This test was done on 35mm film....

 

Chip

True Scott, of all the 2450s I've used, only a couple actually produce more detail at 2400dpi.

The Epson 2450 Photo scanner of mine adds no more detail when used above the sacn bars resolution of 2400 dpi. My other twp Epsons are a 1200U and 1250 perfection both are 1200 dpi. These units give no extra detail when used above 1200 dpi. <BR><BR>The actual resolution of an Epson 2450 photo scanner when used at 2400 dpi; is in the 1600 to 1800 dpi range.

Any number above 2400 is marketing hype. With any scanner (printer too) you can ignore any numbers beyond the first one. Above the optical resolution any more detail is just being made up by the scanner. Stick to the optical resolution and if you need a bigger pixel size use photoshop or genuine fractals to make up the difference.

With the epson 2400; the scan bar is outputs 2400 pixels/inch and steps at 4800 pixels when in 4800 dpi mode. The 2400 wide is split into two 4800 dpi pixels. Only sometimes have I seen sharpeness increases when in 4800 dpi mode; this is when the lines are parallel to the scan bar; and thus the half step of 4800 helps sometimes. Alot of time it is a wash or even appears slightly worse. Thus after much testing; I never use above 2400 dpi with an Epson 2450 scanner.

I scanned a 645 slide at 4800 and got an exceptionally sharp image after the usual Photoshop unsharp masking. I only did this because I wanted an 11X14 at 360 dpi. For 8X10 2400 is plenty. Besides, if you select 4800 and 48-bit, your file size will be huge. I would rather scan at 4800 than resample it larger in PS.

Thanks to you all for the responses. By coincidence I found a Nikon Coolscan 4000ED today, rarely used, for not quite USD 1500 (list price here is around USD 2000) and couldn't resist. Judging from the feedback here it seems to be the right decision to get the scan quality I would like, even if the price is three Epsons.

Where are you that a $1550 scanner (new) costs $2000 (new)?

Austria, Europe. Most of those things cost alot more than in the US. From a current price list, assuming for simplicity that 1USD = 1EUR. 4000ED: $1969, 8000ED: $3890, Canon FS4000: $999 (special offer), Minolta Dimage Scan Multi II: $2499 (special offer), Elite II: $799 (special offer), Epson 2450: $498.

 

I see new 4000ED's going on US ebay for $1200 and start sobbing, but getting one of those would result in 20% taxed added, plus shipping and handling, and the bonus is gone.

 

Same for cameras, the D100 is around $2900 here ...