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Old Sep 20, 2003, 12:28 PM   #1
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Default Photoshop Cropping Question

Hi All,
Simple, but yet I'm lost.
If I take an image (shot in Raw with a D100) and crop it in Photoshop (V5). Do I need to Resize Image or Canvas?

How do I prepare the new cropped picture for printing to different size layouts (4x6, 5x7, 8x10, etc) ?

Apart from any picture messaging, what do I need to do to the image to ensure that I retain the quality and pixel count?
i.e. taking the new cropped image and adjusting it for output to different paper sizes.

Lastly, do I make these changes in Photoshop or the printers (Canon 9100) setup?

Thanks
Eric
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Old Sep 20, 2003, 3:28 PM   #2
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Default Re: Photoshop Cropping Question

Quote:
Originally Posted by eriseman
If I take an image (shot in Raw with a D100) and crop it in Photoshop (V5). Do I need to Resize Image or Canvas?
Image Size shrinks or expands the whole image. Canvas size, leaves image data same size but adds or crops the canvas.

Quote:
Originally Posted by eriseman
How do I prepare the new cropped picture for printing to different size layouts (4x6, 5x7, 8x10, etc) ?
Use 'Image Size' and either go for changing dpi (with resample image data unchecked), or change the image size to desired size.

Quote:
Originally Posted by eriseman
Apart from any picture messaging, what do I need to do to the image to ensure that I retain the quality and pixel count?
If you use Image Size and only change dpi, the image data stays the same. Quality is another problem, if you have a small crop and want to reuse that in 8x10 print, you might see some limitation of best computing power. Using Bicubic resample is best when enlarging, or use an third party plugin genuine fractals. I don't have the url from the last. However what is not in the crop will never show up in the enlargement.

Quote:
Originally Posted by eriseman
Lastly, do I make these changes in Photoshop or the printers
In photoshop. But you can ofcourse experiment; Enlarger by resample image in Photosghop and compare to printer only (dpi) enlarge (it will help to understand these matters).
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Old Sep 21, 2003, 3:03 PM   #3
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I've seen questions about getting the required print size crop up a lot on Steve's Digicams. Personally I managed to bypass the understanding stage by instead of using Photoshop for my printing, using Photostudio which provides a nice little interface for printing. Here's my attempt to make sense of the issues based on what I have read here. I'd be grateful for corrections on issues I have misunderstood:

A picture file my camera produces has a size of 1600 pixels by 1200 pixels and a pixels per inch setting embedded in it of 72.

If it is shown "raw" on a monitor, the pixels per inch value is ignored; each pixel in the picture is displayed as a pixel on the monitor. If I display my picture on a monitor that has been set at 1024x768 resolution, obviously all the picture will not fit on the screen at once; to achieve that I need to use viewer software which processes the picture very quickly to produce a new image which does fit on screen. Interestingly (?) if I have my monitor set at 1024x768 and it measures 14 inches along the bottom (nice size) that means I am viewing at 72 pixels per inch.

On the other hand, if I chuck my picture at my printer driver (say by trying to print it in Photoshop) the pixels per inch setting IS looked at. The printer driver will divide the value of 72 pixels per inch into the pixel sizes of the image to give a required size of 22 by 17 inches (too big for my printer). So before sending it for printing, I need to set the pixels per inch value (as described by Mathilde uP) to the appropriate value for the size of print I want (with the option of saving out the file with the revised value). OK, so I want a 10x7.5 inch print, so I set the pixels per inch as 160 for my 1600 by 1200 picture.

As it happens my Epson printer (the dumb (?) hardware I mean now, not the printer driver software on the computer) only prints at 360dpi (dots per inch) or 720dpi at the higher quality setting (the one I always use for photos). (The adverts mention much higher figures for dpi, but these are more indicators of quality of printing (thanks to small ink drop sizes etc). 720dpi is what my printer and driver converse in). The size of the picture in pixels and the pixels per inch size have told the printer driver what size of print I require, now it has some work to do. It cannot just send out the 1600x1200 pixel image to the printer because at 720dpi that would only give an image 2 inches wide. So the printer software must send an image 7200 by 5400 pixels to the printer; this 4.5x scaling means that in each direction up and across the driver has to produce 9 dots for the printer from what were originally 2 pixels in the photograph. How well it fills in or interpolates the missing dots will have a consequence on how well the print turns out; possible problems could be a too soft or blurry images or strange patterns.

It's possible that the printer driver didn't do as good a job with the interpolation as you would like. There are alternatives to the above route. At the stage in Photoshop above, instead of simply changing the value of the pixels per inch size of the picture, you could instead by ticking the resample box physically resize the image up to 7200 by 5400 pixels (probably choosing to use the best quality bicubic setting). Then sending your big resized image with a value of 720 pixels per inch tacked onto it to the printer driver will mean that the latter won't need to do any resizing of its own to result in the required 10x7.5 inch print.

Alternatives to using this Bicubic sampling in Photoshop are using Genuine Fractals, S-Spline or the various algorithms available in Irfanview to produce the big resized image, or doing the printing using specialist printing software such as QImage.
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Old Oct 1, 2003, 4:14 PM   #4
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Wow! I like to think I know what I'm doing, yet now I'm all confused! :roll:

If I want a 4 x 6 print, I use the CROP tool in Photoshop, set it to 4 x 6 and leave the dpi setting alone. I then crop my image. It will be a 4 x 6 ASPECT RATIO, not necessarly 4 x 6 inches. I can then print whatever size image I want and it will be a 4 x 6 ratio. I do the same for 8 x 10 (4 x 5 ratio) or whatever.

All I watch out for is making sure my cropped area is big enough so when printed, I can stay at at least 300 dpi. If I plan on making a large print, I make sure my cropped area is not too small.

Does this make any sence?

Darrell
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Old Oct 2, 2003, 10:20 AM   #5
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Sorry Darrell if it was my thesis which confused you. I was hoping someone might give it a tick or offer corrections neither of which seem to have happened.

I must assume you really have to crop your pictures based on completely filling whatever aspect ratio your target printing paper gives you. Might seem a shame to be limited in this way. I think having your cropping further hampered by considerations about how close your crop will be to 300dpi would be a bigger shame. Sure any crop will reduce resolution somewhat and may in some cases warrant you giving yourself a slap on the wrist for not doing tighter cropping in camera. But I suspect a good crop is going to make more difference to the impact of your picture than differences between 250 dpi (the best Eric's D100 can achieve in one direction in an 8x10 print) and 200dpi.

On the other hand, if you consistently find yourself making substantial crops, I'd think about using my feet more or getting a longer lens. Otherwise I wouldn't worry too much.

Just my two lesser units of currency's worth.
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Old Oct 2, 2003, 10:36 AM   #6
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Just curious as to why resize before printing and worry about all that. When I print a picture I just tell my image editor to print at whatever size I want and there it is. No resizing or cropping (unless I want to specifically do so) needed. Just print and that's it. The software takes care of the details.

Now if you wish to print at a different aspect ratio, then cropping is needed but I never resize for printing.
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Old Oct 2, 2003, 11:52 AM   #7
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Hi Luis. My understanding is that by doing the resizing yourself, choosing what software (algorithm) does the resizing and perhaps doing some processing after the resizing (most likely sharpening), this allows you greater control and probably the ability to maximise quality of results. Although I believe this tends to become most significant when you wish to achieve considerable enlargements such as for posters I've seen people claim that in attempting to produce good quality 10x8 prints from 2MP cameras they get better results from using specialist software such as Genuine Fractals or S-Spline to interpolate up to required size for printer hardware.

For anyone interested in whether they can improve on current results, there is a demo of Qimage at :
http://www.ddisoftware.com/qimage/demo.htm
Although many say this isn't the easiest software to learn how to use, it's not difficult to get it to print out a maximum size print for your printer at best quality settings which might be instructive for comparison purposes.
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Old Oct 2, 2003, 12:29 PM   #8
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Well, I normally print smaller than the size described by the picture's dpi, so the resizing is normally not a big issue - the results normally come out good enough.

Anyway, I only print myself to generate proofs as I take my digital images to a photo lab for printing in real photo paper which gives me far better results than my ink-jet printer for pictures I intend to keep or frame.
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Old Oct 2, 2003, 12:35 PM   #9
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Quote:
Originally Posted by normjackson
I've seen people claim that in attempting to produce good quality 10x8 prints from 2MP cameras they get better results from using specialist software such as Genuine Fractals or S-Spline to interpolate up to required size for printer hardware.
My camera is 3MP but I have printed in 10x8 pictures taken using a lower resolution (about 2MP) with amazing results. That particular time I was using only the camera's internal memory and shooting at a lower resolution to save space. The level of detail obtained in that picture was amazing. I used one of those Kodak Picture Maker kiosks that uses a dye-sublimation printer. The line between 2 and 3 MP is very fine in terms of quality.

It depends a lot on the camera and on the printing process itself aside from any post-processing you might need.

But we are getting off-topic. ops:
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