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Author Topic: Printing with Qimage from Scanned Slides  (Read 7893 times)
adydula
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« on: April 23, 2010, 05:41:44 PM »

Hello,

Been using QIMAGE for years and like it very much.

I just bought a V500 Epson scanner and have started down the path of scanning old
slides and Black and White negatives.

I understand for printing at 300 dpi that for a 4x 5 print this means 1220 x 1500
for 8 x 10 print this means 2400 x 3000 ...based on the basic rule of 300 x the width or lenth of the print
you want to do.

So my question is:

How low of a dpi scan setting can i get away with and let QIMAGE do the resizing magic...can i get away with lower than 300 dpi in scanning or do i have to pay the piper to get the job done right?

Maybe its more like if I want to print a really noice 8 x 10 and scan at 2400 dpi this is the best but can I scan at say 1200 dpi and will QIMAGE fill in the blanks so to speak??

Thanks in Advance.

Alex
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Terry-M
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« Reply #1 on: April 23, 2010, 08:07:21 PM »

Quote
I understand for printing at 300 dpi
That, to some extent, is an urban myth Wink
Qimage was originally developed to make A3 prints from a 2M px camera and since then it's been improved considerably.
You can get a good print with 100 ppi, 300/360 is better and should be more than adequate.
A 35mm slide scanned at 2400ppi will give about 330 ppi on a 10" print; and the same for a 5" print where the negative was scanned at 1200 ppi.
Why don't you compare test prints from a slide scanned at both 1200 & 2400 ppi and try a 10" print from each. You may be pleasantly surprised. Tell us how you get on.
Terry.
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adydula
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« Reply #2 on: April 24, 2010, 01:31:20 AM »

2 prints 8x10's one at 1200 dpi and one at 2400 dpi, they look identical, can not tell them apart..

So...this is good..this means I can scan at lower dpi and still get a decent print with QIMAGE.

So how far can you play this game?

If I scan at 3200 or 4800 dpi will a print at 17 x 22 from my Epson 3800 still look good?

Alex
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Terry-M
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« Reply #3 on: April 24, 2010, 08:09:11 AM »

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So how far can you play this game? If I scan at 3200 or 4800 dpi will a print at 17 x 22 from my Epson 3800 still look good?
Try it. If you don't want to use a full sheet, print "test strips".
Terry.
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adydula
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« Reply #4 on: April 24, 2010, 10:03:38 PM »

Gosh Terry..

Your making me do all the work!

I will try ....If I can scan at a lower dpi and let Qimage interpolate up to 17 x 22 this would save me scan time and disk space.

The 1200 dpi scan is really very nice compared to the 2400 dpi one, again I cant tell  any real noticable difference at a 8 x 10 print size.

So at least I can scan at 1200 dpi for those famliy shots that I might someday do a print of but never any larger than 8 x 10.

Its finding the magic sacn dpi for those few I want to print up to a 17 x 22 on my Epson 3800 etc..

Ok  back to the testing..

Alex
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adydula
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« Reply #5 on: April 25, 2010, 08:17:21 PM »

Ok,

I took three scans of a 35mm Kodachrome slide, winter scene, snow and leafless maple trees...lots of bare branchs on the trees for a good resolution test.

Scans were at 2400, 4800 and 6400 DPI on the Epson V500 scanner with the included Epson Software.
I used medium USM, medium grain reduction, color correction and HIGH dust removal.

I then took 3" test strips from each and printed them out on a single sheet of 13 x 19 PGPP (Epson Glosst Prof) paper. So the 35mm slide was enlarged via Qimage to a 19" length.

I can see little or no difference in either of the scanned prints!!!

Now my wife consitently picks out the LOWEST 2400 DPI scan as the best resolution based on shadows on the snowy areas of the print!!!

So  I guess if I print out at 2400 dpi I should have no issue making a 13 x 19 print that is virtually identical to one printed from a 6400 DPI scan using Qimage!


I was thinking that taking such a small 35 mm slide scanning and printing to a large print is a real tough test of the technology employed to be able to get a decent print etc...

I was wondering again if the negative or source area increased what would happen to this relationship>

Would the results scale if the negative was a larger format? I would think so.

If anyone has any experience in this area please share this knowledge!!

All the best

Alex

 
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Terry-M
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« Reply #6 on: April 25, 2010, 08:36:50 PM »

Alex,
Quote
Would the results scale if the negative was a larger format? I would think so
Rather than thinking terms of ppi as the scan resolution, think of the pixel size of the resulting scan.

BTW. I'm using ppi as it's a more correct term; dpi (= dots per inch usually refers to ink jet printers and the their spray pattern)

Back to larger negatives, your 2400 ppi on a 35 mm slide is equivalent to a digital image of about 3300 x 2200 pixels. This gives only 174 ppi on the print, quite low but Qimage can obviously cope with it.
So for a larger negative, aim for a similar pixel size, long side about 3300 pixel.
I would comment, if these are for "archive", I'd want to scan at a higher resolution, store them on DVD's and jsut keep lower resolution versions (use Qimage to produce them) on your PC for viewing.
It depends what your aim is, something for posterity or easy access and a few prints.

Quote
used medium USM, medium grain reduction, color correction and HIGH dust removal.
I would worry about the High dust removal setting, that could be degrading the image; time for another test  Wink
Qimage Blemish removal is good providing there are not too many spots to remove.

Terry.
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rayw
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« Reply #7 on: April 25, 2010, 10:02:55 PM »

Hi Alex,

Looking at it from another direction -

Doing some rough comparisons, considering the narrow width/height of the slide (about one inch). You want to print at say 720dpi on 13inch wide paper, using Qimage. Now, in practice, printing with Qimage to larger prints, bearing in mind usual viewing distances, etc., you can start off with with a much lower resolution than 720ppi. Fwiw, the height of a canon 40d camera image is about 2600 pixels, and I can get good prints larger than your final size with those images and Qimage. Now, allowing for a the sensor size, if the 40d was a full 35mm frame, at same pixel density, then it would equate to 3900 pixels - The 5d, which is full frame, is about 3000 pixels, and that pushes the lenses to their limits, according to some (but it is not just ppi/dpi that matters).

So, bearing in mind the above, and the likely quality of the slides, I would think that 2400ppi scanning would be quite satisfactory, as you have found. I believe the native optical resolution of your scanner is 6400ppi, so possibly a scan at 3200 or some other factor of 6400 may be faster or give a better result than 2400, I think I would try 1600, if it speeds up the process. You can't beat testing things out for yourself  Cheesy If it is really important, then as Terry says, don't clean up the image in the scanning software, and I would scan at 6400ppi.

(I think you may have made a few typo's in your description, or maybe it's my misunderstanding, but you don't want to/can't print out at 2400 dpi using
Qimage)

The rule of thumb used to be, 30/40 years ago, if you wanted to print at same size as the original, you scanned at 1.5 times the the ppi of the final print resolution, but that was before ink jet printers were around, iirc. (Somewhere, I've still got my early canon scanner - monochrome only, which I converted to colour - using three filters on sliders, scanned three times and combined in some software written by Computer Associates - who now, like many, seem to be a shadow of their former self...)

Best wishes,

Ray
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adydula
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« Reply #8 on: April 26, 2010, 11:19:50 PM »

Terry,

I turmed off all the filters, and compared HIGH Dust removal vs NO Dust removal.

They are virtually identical at a slide scanned in at 2400dpi on the V500 scanner.

This was at 200 and 300% in CS3.

Comparing the USM default setting comapred to what CS3 can do its amazing how good the scan usm applied at the medium setting is...

Ok think I am ready to get into mass scan mode, 2400 dpi for my so-so slides and 4800 for the good ones and call it a day.

Alex
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Terry-M
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« Reply #9 on: April 27, 2010, 07:37:16 AM »

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Ok think I am ready to get into mass scan mode, 2400 dpi for my so-so slides and 4800 for the good ones and call it a day.
Thanks for reporting back, you are going to be very busy  Cheesy
Terry
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