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Old Dec 5, 2006, 6:13 AM   #1
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Hi all. I'm pretty new to photography and have had my Fuji S5600 for only a few months but really want to learn more about it all.

My question is if I take a picture (in this instance of the moon) using the 5 megapixel setting on fine compression, how much could I crop the picture and still have it printed out on a standard 5x7 print? On the 5M (fine) setting the images are 2592 pixels times 1944 pixels, but a pic of the moon has obviously alot of black background that doesn't add to the pic. I want to have the moon as big as possible in the print but still want it as sharp as possible.

Any help would be greatly appreciated. Thanks.
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Old Dec 5, 2006, 6:38 AM   #2
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The only real answer is, "Try it and find out".
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Old Dec 5, 2006, 10:48 AM   #3
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This web article may help you understand digital printing and resolution:

http://photo.net/learn/resize/
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Old Dec 5, 2006, 3:23 PM   #4
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blindsight wrote:
Quote:
This web article may help you understand digital printing and resolution:

http://photo.net/learn/resize/
Thanks heaps for that. I'll give it a good read and see if it makes sense to me.

I understand that with a digital camera alot of what you do can be achieved through trial-and-error (because the unwanted shots can be just deleted) but that same logic doesn't apply with actually printing out prints because you'll potentially end up with blurry / unclear shots that you've paid for to be printed - hence my question.

Cheers.
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Old Dec 5, 2006, 4:47 PM   #5
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I also read the same question you posted over at Fuji forum, and Bill's reply. Although I don't print pictures at home (only at photo labs), I also want to give it a go.

I think Bill is on the right track, except after reading the above article myself, I noticethe difference betweenPPI (pixels per inch) and DPI (dots per inch). Maybe Bill has gone down the wrong track.

Say your moon in the 5M (2592 X 1944 pixel) picture only measures 200 pixels across. You crop it tomake a 5" X 7" print, say stretching the diameter of the moon 4 inches across the paper (not all the way across):

The PPI of the moon on the print = 200 pixels per 4 inches = 50 PPI

which is far too low for the number they recommend (at least 180 PPI; I also heard > 200 PPI)

Therefore, to reach the goal of 200 PPI, if you are printing your moon across 4 inches on the 5" X 7" paper, you need to frame the moon so that it is:

200 pixels X 4 inches = 800 pixels in diameter

Which means on your highest 5M setting, the moon needs to be filling at least 40% of the height (1944 pixels) of the frame, or at least 30% of the width (2592 pixels) of the frame, so that you may have decentdetailwhen printing the "pie" out in 4-inch diameter on paper.

Remember, if you want to print it out larger, say across 8 inches span (on 8 X 11 paper) instead of 4 inches, you need to double the number of pixel dimension.

So I guess, the estimate of the (linear) pixel size of your crop would be:

PPIwith adequate resolution X number of inches you want your crop to print out to

I am not exactly sure if this calculation is correct - I am presuming the PPI (pixels per inch) is a linear parameter and not 2-D (pixels X pixels). Therefore, everything I said may be off by 4-folds altogether!

You also have to remember that the recommended numbers are only guidelines and not "magic numbers" - the print quality will also be affected by various artifacts (JPEG compression, noise/ noise reduction etc.) which are integrated into the picture. Maybe taking RAW pictures canhelp to reducethese additional factors ? (But you still need to do post-processing of the RAW anyway)

Therefore, there is still a component of "trial & error". However, at least this estimate may be a starting point to see how much your camera's MP can do.

In any case, the crop should NOT be enlarged by software resizing at all cost.

I am not saying the DPI does not affect the quality of the print - the maximum DPI of the printer determines the final print quality. However, in the"photo" settings, the printer driver would have set the DPI to the highest value for the best quality, trherefore this is not a parameter that the user has to particularly worry about.

I also found this article:

http://www.microsoft.com/windowsxp/u...stquality.mspx

There are tables withrecommended maximum pixel size prints for different PPI values - the print sizes are quoted for whole pictures - I guess if you are talking about cropping, the size of the crop should correspond to these numbers.

I hope I got this right, let the discussion continue!


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Old Dec 5, 2006, 5:01 PM   #6
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You can cut the cost of trying things out by printing 4x6" crops of the larger image. Just pick the area with the most detail for the test.
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Old Dec 6, 2006, 4:14 AM   #7
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Blindsight - you have got some very interesting points there. I have looked at the properties of my saved pictures (prior to any sort of editing) and it's telling me this (among other info):

Width: 2592 pixels

Height: 1944 pixels

Horizontal Resolution: 72 dpi

Vertical Resolution: 72 dpi



Now this proves, I think, that the dpi is expressed in linear terms but my real concern here is why is my dpi so low when I'm using the highest quality setting on the camera (short of the RAW format). The other thing that got my attention is when I looked at some pics that I have on the pc from my old Kodak 4530 they're stored at 230 dpi. I thought my S5600 was supposed to be better than the old 4530...

Any thoughts here?




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Old Dec 6, 2006, 11:56 PM   #8
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I am still a bit confused about the DPI stuff myself.

If you read the article (link I posted earlier) - under "Dots Per Inch", they describe that it is NOT relevant to the image quality at all, because it is a value related to printer printing quality.

I have also read other posts in one of these forums here, that some people try to explain that the "DPI" value recorded in the EXIF of the image is rather arbitary, just a number to fill that particular field/ blank in the EXIF data - again DPI has nothing to do with the image quality. Problem is, I can't find any of these posts which give a better explanation than mine.
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Old Dec 7, 2006, 3:50 AM   #9
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blindsight wrote:
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I am still a bit confused about the DPI stuff myself.

If you read the article (link I posted earlier) - under "Dots Per Inch", they describe that it is NOT relevant to the image quality at all, because it is a value related to printer printing quality.

I have also read other posts in one of these forums here, that some people try to explain that the "DPI" value recorded in the EXIF of the image is rather arbitary, just a number to fill that particular field/ blank in the EXIF data - again DPI has nothing to do with the image quality. Problem is, I can't find any of these posts which give a better explanation than mine.
Thanks again for your response. I too have found a few articles/posts regarding dpi and have come to the conclusion that I perhaps need to ignore anything to do with dpi.

I've actually got a thought. All I really need to worry about is knowing how big could I potentially print the original photo at the 5M setting. I've read that at that setting I could print prints up to 11 x 8 (inches) in size. The prints, unedited, are 2592 pixels by 1944 pixels in size, which means that there are approx 235 pixels per inch (linear). I say approx because clearly the ratio of 2592/1944 is not the same as 11/8 so there is a bit of natural cropping that would occur if I had it printed in those dimensions. Now, using that as a guide, if I wanted to crop a section of my photo to a size of say 7 x 5 I would have to make the image somewhere around 1639 x 1237 in size (1639= 2592 divided by 11 and then times by 7). The same logic applied toproducing a 6 x 4 crop gives me a print sized at 1413 x 1060. Do you think any of this makes sense?

I think I might just bite the bullet, using thislogic, and do as BillDrew suggested and tryit and see how it works out.
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Old Dec 7, 2006, 9:00 AM   #10
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This is an excellent interpretation, I totally agree! In fact, you pointed out the resolution of your 5M setting is about 235 PPI (2592 pixels / 11 inches), thisis probably the most useful number about the performance of your camera.

This is similar to what I came up with:

PPI (target resolution setting) X number of inches (linear dimension) you want to print

= the least number of pixels (linear dimension) youmust have in your crop

(you can also work this equation backwards to determinethe maximum number of inches you can print your crop out to, by measuring the linear dimension of the object in the pictureyou want to crop)

If the PPI numbers recommended by internet posters are correct ("at least 180 PPI"), you may still have a bit of "resolution" to play with (your camera's 5M setting gives you 235 PPI). If you want to experiment andenlarge the crop, you can use the re-size tool of image editors, and set it to a lower PPI of eg. 180, 200 etc. (make sure it is not in "cm/inches" or "DPI" modes), with the "maintain aspect ratio" box checked.

Again, this manipulation would be a trial & error process - you may find that the quality of the original picture barely adequate (remember all the JPEG compression, noise/ noise reduction artifact), and these defects are greatly exaggerated when you enlarge the picture. The only way is to print out test shots and let your eyes be the judge.

Again, I wonder if capturing the imagesin RAW, doing image editing (sharpen, NR etc.) afterwards, and re-saving it in alossless format (like TIFF with LZW compression), may help?

I also want to apologize forthis confusion:when I say "Bill's reply" I mean "bill soper" over at the Fuji forum, where you posted the same question.

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