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Old Jul 23, 2004, 8:19 AM   #11
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Well again JimC thankyou for your reply.

As it stands I just need to know if the Canon 300D or the Canon 10D is up to the job of being good enough for litho printing, which everyone seems to agree it is. Great I get a new toy!

That's when I can get on with playing and finding out what works best for my needs and then I'm sure allot of your points will become clearer, but hey it means I can get back into what attracted me to photography in the first place, experimentation.

I feel its about time I stop hassling you guy's apart from one more thing, book suggestions would be great, maybe something along the lines of the bible that is basic photography?
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Old Jul 23, 2004, 8:21 AM   #12
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As it stands I just need to know if the Canon 300D or the Canon 10D is up to the job of being good enough for litho printing, which everyone seems to agree it is. Great I get a new toy!
Quality is subjective. What size prints will you need? Again, the resolution needed for the best detail is controversial, but I think that the vast majority of users will tell you that the actual detail captured by a camera like the EOS-10D is more than adequate for most uses when compared to 35mm film.

Look at the charts in my original post for examples of the quality you can expect from a given resolution sensor at a given print size. Again, there are techniques to "rez up" (interpolate) an image if the pixel density is not sufficient, but this will not increase the detail captured. As forum member Eric S. mentioned earlier in this thread, some subject types work better with this technique, compared to others.

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I feel its about time I stop hassling you guy's apart from one more thing, book suggestions would be great, maybe something along the lines of the bible that is basic photography?
You are not hassling us. In fact, I enjoy these types of discussions, and I think you'll find that most other members here do, too. This is a great place to interact with others that are interested in digital photography.

BTW, I have not personally gone through it, but Forum MemberMikefellh posted a link to this site in another post a while back. It's an online course youmay want to lookat. Based on a quick skim of it's contents and some of it's text,it looks to be a very good place to learn more about digital photography:

http://209.196.177.41

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Old Jul 23, 2004, 9:57 AM   #13
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I'd echo JimC that I like this type of talk too. It's a refreshing change from "What camera should I Buy?" You supplied a situation "will this camera do this?" and asked questions around that topic. Much more interesting.

JimC,

This might be a fine point, and beyond Grant.smith, but this is why I mentioned upsampling. If you have a printer that prints natively at 320DPI and you give it something at 200DPI (like you suggest is a good DPI... and I'd generally agree with) then the printer is upsampling the image. The data isn't there to print at the size you requested, so it is making data to do so. Now, personally, I'd rather do that myself in PhotoShop and then I can do selective sharpening and other things to enhance the image further before printing.

So while you weren't explicitly talking about upsampling, you actually were. The printer is doing it in your name.

This part I know less of, so others should correct me here.
It can also be said that the printer is decomposing the pixels that you feed it into really tiny dots (if it's an ink jet.) In doing so I believe it combining a bit of neighboring pixels's data in some of the drops of ink its putting to paper for the area where the data from two pixels border each other (i.e. a smooth transition.) So it's going to do some data processing and translation any ways. This is actually a good thing.

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Megapixels is actually the area it will cover?
No. Megapixels is the number of dots of color you have information about. How you tell the printer to put those dots to paper is your choice. You could tell it to turn it into a 2x4' picture or a 2x4" picture. What will make it look better or worse is (among other things) the subject and how many dots you have. The less data, the less detail. The larger the print, the more the lack of detail shows.

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Everthing I have learnt in print over the years does not apply to digital photography?!
No! The world is not that bleak! I agree with JimC that what you know about photography almost totally applies to digital. It isn't a whole new world. You know about exposure, you know what an fstop & ISO are. These concepts are basically the same.
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PhotoShop (my preferred picture image package), does not give me a true representation of image size?
I generally agree with JimC here. You can turn on rules in PhotoShop that will take the DPI setting and show you how large a print you'll get with the current picture and current DPI. But a monitor is not a printer and really only approximates what a printer can do.
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Basically if it covers the area of print, for example A4 it is good enough to be reproduced through a Litho or Digital print process?
Yes, I would generally say that is true. And if you don't have enough data to make the size print you want, you can always try to use upsampling to create the data. Is it perfect? No, but it can work.

It the printing world it just becomes a bit trickier because you have to take the hunk of data that represents the picture (those pixels) and tell the printer how it should put it to paper. That includes telling it "you see all this information that represent dots of color? Print it so that there are X dots on an inch of paper."

Eric

Ps. As always, questions of quality and "good enough" are subjective. I like those 11x14 pictures I had printed from my 10D (in some cases, from cropped images!) To you, they might be crap. I can only tell you want I experienced and you can take it as you will.
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Old Jul 23, 2004, 10:12 AM   #14
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eric s wrote:
Quote:
This might be a fine point, and beyond Grant.smith, but this is why I mentioned upsampling. If you have a printer that prints natively at 320DPI and you give it something at 200DPI (like you suggest is a good DPI... and I'd generally agree with) then the printer is upsampling the image. The data isn't there to print at the size you requested, so it is making data to do so. Now, personally, I'd rather do that myself in PhotoShop and then I can do selective sharpening and other things to enhance the image further before printing.

So while you weren't explicitly talking about upsampling, you actually were. The printer is doing it in your name.

This part I know less of, so others should correct me here.
It can also be said that the printer is decomposing the pixels that you feed it into really tiny dots (if it's an ink jet.) In doing so I believe it combining a bit of neighboring pixels's data in some of the drops of ink its putting to paper for the area where the data from two pixels border each other (i.e. a smooth transition.) So it's going to do some data processing and translation any ways. This is actually a good thing.
Eric S.

Yes, you are absolutely correct. The printer type used can make a big difference. For example, with a Dye Sub type printer, you may need more pixel density, compared to an Ink Jet Printer.

Ishouldhave clarified what I mean by quality. What I should have said, was that I cannot personally see any additional detail in an image, going to a higher pixel density (as captured by the camera), once you get to around 200 Pixels per Inch for the print size you want (regardless of whether the image is being "rez'd up" or not).

Of course, quality is subjective.


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Old Jul 23, 2004, 12:02 PM   #15
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I had an interesting thought while reading your comment.

I wonder if any printer does a better job than I could in photoshop at upscaling an image. I mean, there is competition in the printer space and I'm sure time and money is spent on getting that to work well. And who knows the capabilities of their printer better than they do? So they could do it in a way which best fits how the printer works.

I bet it's printer specific but it would be interesting to test. That might account for some of the "300DPI is better" - "No 200 DPI works great!" discussions. Unless the printer is the same, it isn't really fair to compare at that level. (And I've heard statements that if you feed them too high a DPI, the printer will drop data. Not surprising, but that could easily effect quality too!)

Eric
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Old Jul 23, 2004, 12:42 PM   #16
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Eric:

This is controversial, but some users advocate interpolating to a very specific ppi number for different printer types.

For example, Epson printers print in output resolutions that are in multiples or halves of 360 (like 1440 x 2800)

Therefore, some users advocate that Epson printers do their best when they are given image input files that have a resolution of 360 ppi, or one half of that (180 ppi) for larger prints.

If you look at Mike Cheney's QImage Pro, it is designed to automatically interpolate the image for the best output from a given printer type, so that you don't have to worry about it. It also includes interpolation algorithms like Vector, that are supposedly much better than BiCubic.

http://www.ddisoftware.com/qimage/

I have no personal experience with this method (interpolating myself to a specific ppi for my printer, or using software like QImage Pro to do it for me).

When I need to crop an image for printing (when I give it to others for their printers, or post it at photoaccess.comso that they can order prints from it), I do usually interpolate it myself to 300 ppi, using the Lanczos Algorithm included with the free Irfanview software.

I'll usually post two versions of some photos (one cropped for 4x6" prints, with another cropped and interpolated for an 8x10" size) -- labeling them as such.

I figure this is a "safe bet" (300ppi) for any printer type they'll likely want to use. I post a lot of photos of family parties, etc. in albums at photoaccess.com, since they don't charge anything for album space. This also lets friends and family order prints as needed (even if they don't have printers).

Here is an example of an image I cropped recently (for both composition and print size), then interpolated back up to 300ppifor an 8"X10" print size target.

Despite a relatively heavy crop, it prints a stunning 8x10. It was taken by a little 5MP pocket camera, so redeye was bad (and I should have spent more timeon'em). However, at 8x10" print size, the eyes are small enough so that the corrections are not reallynoticeable (unless you are looking for the corrections, knowing about how bad the redeye was to begin with). :-)

In any event, I printed copies of this for several family members (they are my wife's grandchildren), and the results are quite stunning when printed (keeping in mind that this was from a pocketable camera, using it's built in flash, and wasn't even taken using it's highest quality JPEG Compression)

Original (2592 x 1944 pixels, if you look at the original size)

http://www.pbase.com/image/28335973

Cropped (heavily, since I cropped the kids out of a landscape oriented photo, to make a portrait oriented photo -- although it's not rotated in the album). I then Interpolated (with Lanczos) back to 300ppi for an 8"x10" print (3000 x 2400 pixels, if you look at the "orginal size"). I didn't bother to try and do much with it other than the crop, redeye reduction, and interpolation. If I wanted to go larger, I'd clean it up a bit.

http://www.pbase.com/image/28336041

Note, that as youpointed out, this is a portrait, so results may not be as good withphotos with lots of detail like foilage in landscapes, etc.
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