I recently had my first experience with digitial, having one of my 4X5 chromes drum-scanned and then printed on Crystal Archive. I was pleased to see the result is superior in many aspects to a 16X20 Cibachrome of the same chrome that I had done as a control. I do have a few open questions, however:

Is there anything to be gained by having the 4x5 chrome scanned at 300MB as opposed to 100MB when the anticipated print size will be 16x20?

How does Crystal Archive Supergloss compare to regular Crystal Archive glossy?

Is there any clear leader as among West Coast Imaging, Bill Nordstrom (Laser Light), Color Folio and NancyScans?

Thanks.

-- Josh Divack (jdivack@compuserve.com), August 21, 2001

Answers

JOhn....start with the final dpi required by the printer and work backwards.... for example, LJ or Chromeria printers peaks out around 200 - 250 dpi. Ink jets are a bit more thirsty and require up to 300 - 360 dpi. A scan any larger than this would be exceeding the printers capability, so just a waste, unles you have other uses for the scan. Check with each type of printer you go to... Now to calc. the files size.... use this simple formula...

In this example,

16x20" print 200 dpi 8 bit scan (you can scan up to 16 bit, but not much accepts it yet) 3 Channels, RGB

16x20x200x200*8/192,000*3 = 38 MB

So in this example, any thing over 38 MB is overkill and a waste of space.

To calc. how much dpi you need to scan at to accomplish this, take the enlargement factor (4x) x the end dpi, which is 200, or 800 dpi...this can be easily scanned at home with an expensive flatbed scanner. Now if this was 35mm film, the dpi of the scanner would need to be 16x200=3200 dpi, a much more expensive scanner...another benefit of shooting larger 4x5 film. Hope this helps

-- Bill Glickman (bglick@pclv.com), August 21, 2001.

Although for your print 100mb is enough, if you scan at $300mb, you'll have an "electronic dupe" of your chrome for archival purposes. You won't need to rescan it, should you want to make a large print, and maybe won't need to do the digital work twice.

Supergloss, as it name implies is more glossy than regular Crystal Archive glossy. It's quite comparable to Ilfochrome in look.

-- Q.-Tuan Luong (qtl@ai.sri.com), August 21, 2001.

The LightJet prints at 304.8 DPI (12 dots/millimetre).

You will hear the phrase "Scan once for many purposes".

To apply this to your example: You could scan at exactly the resolution for a 16x20 print. Then you might do some work in Photoshop (curves, a little dodging and burning, etc.). Then get a print made. Later on, you want to make a larger print. Rescan, do the Photoshop work again, etc.

Or, you could scan at a very high resolution, make your adjustments (this becomes your "master" file), and then "target" the image for your final 16x20 print. What does "target" mean? Simply this: resize for the final 16x20 print, and apply sharpening for that size. Later, you can target the same master file to a different size.

The "scan once" philosophy means that you pay for one scan, thinking towards the future.

If you know that you will never print larger than 16x20, then you can safely scan for that print size. But, if you make larger prints in the future, you will have to pay for another scan, later. (ie. you can save some money now, and pay more in the long run.)

-- Michael Chmilar (chmilar@acm.org), August 21, 2001.

Mike, the reason I stated 200 - 250 dpi for the LJ and Chromeria is because Bill Nordstrom told me he tested these extensively and that no discernable difference could be seen above 200 dpi, he used 250 as a max. upper end dpi.

-- Bill Glickman (bglick@pclv.com), August 21, 2001.

Thanks all. Could I ask who you (respondents) use for drum scanning and lightjet output?

-- Josh Divack (jdivack@compuserve.com), August 21, 2001.

Josh:

First, I agree that 100MB is more than enough for a 16x20, and from my tests, there is no UNIVERSAL improvement in using 300dpi over 200dpi for the LightJet. Some images are improved at 300dpi, others aren't. By the way, I have heard that the newest LJ uses an even 200 and 300 instead of 203 and 304dpi (actually 80 and 120 pixel/cm. Heaven forbid too much metric invade our shores.

But... as others have noted, if you only scan at 200dpi for 16x20, you can't go larger without another scan. The 300MB scan provides enough data to reproduce the original on film if necessary. If that is not of interest, I would suggest you scan at 300dpi for a 16x20 print, then you can always enlarge by 50% by just dropping down to 200dpi.

I have used Bill Nordstom and WCI, both with excellent results. My impression is that Bill does a bit more "interpretation" on average than WCI. That can be good or bad, depending on whether you like the result. Bill has been excellent to work with. WCI is more adaptable if you want to do your own digital manipulations, and just use them for raw scans and final output.

-- Glenn C. Kroeger (gkroeger@trinity.edu), August 21, 2001.

There is virtue in scanning at a higher dpi: allows for some cropping and getting back to intended output size; allows you to edit in 16 channel, then convert to 8 channel for printing. For my first run at an Epson inkjet print I work at 400 dpi, coming down to 360 dpi near the end of adjustments. On the other side, if you have enough information in that file for a 20 x 30 print and only are doing an 8 x 10 one, getting down takes computer memory, time and you are constantly resampling your image. Thus, I still believe in multiple scans. Once everything is set up, say on a flatbed, it doesn't take that much more time to do scans-for example-at 100 percent at 360 dpi (kind of a digital contact print; a file I may examine for quality, Newton's rings, etc. before doing the follow-on scans) 600 dpi, 1200 dpi, and 1800 dpi. Archive the masters and work with copies.

-- David Stein (DFStein@aol.com), August 21, 2001.

Here are some conversions from a chart I have regarding print-file size... The minimum for the lightjet 5000 is 150ppi, good is 200ppi, max is 304.8ppi......... I will list the file size needed to print the corresponding image size in the order- minimum ppi-150, good ppi-200, max ppi 304.8.

11X14 print- 9.92mb, 17.7mb, 41.0mb......... 16X20 20.6mb, 36.7mb, 85.1mb........... 20X24 30.9mb, 55.0mb, 128mb........... 20X30 38.6mb, 68.7mb, 160mb.......... 30X30 57.9mb, 103mb, 239mb............ 30X40 77.3mb, 137mb, 319mb...........

Its up to you how big you want to go or how many ppi you want to print. However, image perception aside, if it will do 304.8ppi- why not use it? It sure wont hurt.

-- michael kwiatkowski (scvcym8567@aol.com), August 21, 2001.

Josh - if you're paying for drum scanning, you may as well get the largest optical file possible as a master, then resize as required for subsequent prints. You are probably coming to the conclusion that with 4X5 you don't need high dpi in your scans for your smaller prints - why not get your own low end scanner? On another point, should any of your images require some work in Photoshop, or other software its usually easier and cleaner to work with a large file, and then resize - you're less likely to see the artifacts.

-- Michael Mahoney (mmahoney@nfld.com), August 22, 2001.