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Old Oct 25, 2003, 4:10 PM   #1
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Default rule of thumb? xx pixels = how big a print?

All,

Is there a rule of thumb for the number of pixels you need to be able to get a good quality print?

i.e. does 4mp = A4, 6mp+ = A3?

I realise its not as simple as that, but their must be some general rule.

I have a Canon G3 that I use as a point a shoot, and I don't think I can get prints any bigger than 8x10 out of it. What I thought were high quality scans of my Velvia, have turned out to be expensive 3000x2000 images. What sort of print size could I expect to get before the average person would see the difference between film SLR and digital printing?

Martin
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Old Oct 25, 2003, 5:50 PM   #2
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This article should help you to undrstand the relationship between image resolution and printed image size:

http://www.tssphoto.com/repro.html
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Old Oct 27, 2003, 11:53 AM   #3
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That article was informative, but maybe too technical.

In my various digital camera photo printing experiences:
2mp = OK 4x6
3mp = Good 4x6, 5x7 and OK 8.5x11
4mp = Excellent 4x6, 5x7, Good 8.5x11 and OK 11x17
5mp = Excellent 4x6, 5x7, 8.5x11, Good 11x17 and OK 13x19
6.3 mp = Excellent 4x6, 5x7, 8.5x11, 11x17 and 13x19.


This of course will vary depending on your camera's quality and its settings for taking pictures.

Hopefully that helps answer your question.
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Old Oct 28, 2003, 2:55 AM   #4
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Default All useful.

Thanks for the posts.

I have at least a good idea of what to expect. I sat down and worked my way through the maths of the article, and it all seems to make sense, and the summary was useful as well (I can now pass that on to my less interested friends who will take it as gospel)

Martin
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Old Nov 1, 2003, 8:38 PM   #5
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Default minimum resolution for inkjet prints

Martin,

The article that "jawz" referred you to is intended for laserprinters and RIP processing.

For inkjet printers much of details of that article are irrelevant. A simpler criterion that many people use is that your image when printed must have at least 200 pixels per inch. On Epson printers, some people swear that 240 pixels per inch is the minimum because it is one third of the 720 dpi native processing of the printer. Settings of 1440 and 2880 are just further multiples and further interpolations.

When processing an image in Photoshop, I always check "Image/Image Size" command to see what resolution I'll have at the size the image will be printed at.

200 pixels/inch mimum is much easier to remember and more relevant to inkjets than file sizes that depend on how much an image is compressed. Try your own experiments. At 100 pixels/inch, I bet you'll see jagged edges. Above 200, these jaggies will not be noticeable at normal viewing distances.

My two cents,

Gordon
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Old Nov 4, 2003, 5:37 PM   #6
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Default Inkjet printing, colour gamuts (?)...

Hi all,

Thanks for the replies so far. Things are starting to get complicated now.

I have a series of colour scans - kodak photo CD's, scanned at a professional lab. Up until now, I have only viewed them on a laptop screen.

Now, I have loaded them onto my desktop PC, with a Sony FW900 (24"wide screen monitor), and I am trying to view them in Adobe Photoshop (Elements 2, and Photoshop 5), and eventually print to an Epson 2100 (2200).

The problem is:
I don't (or can't find) an ICC profile for the source scans - I am not even sure what scanner/method was used.
I've loaded the 6500 ICC profile for my monitor as the output ICC.
Printing? I get lost at this point.

My understanding is that the ICC profile tells the software what colours were available at each stage. i.e. the same colours that the scanner can rcognise, the monitor might not be able to display, which in turn will be different from the colours that can be printed.

In my head, I have a Venn diagram of what this all means - and I think it means I might as well only scan, display, and print colours that all three have in common - but this just sounds completely illogical.

What would I need to do in Photoshop to:
a) View the image as close to the way it was supposed to be viewed
b) Make sure that when I print it, it comes out as close to what I am seeing on screen.

The scans that I have just don't seem to be displaying the full range of colours - i.e. there is serious banding on screen.

Any help appreciated.

Martin (starting to wich I hadn't got into all this, and just stuck with getting slide film prints made up)
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