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DavidZahir
12-30-2010, 08:17 AM
Printing standard is 300 dpi.

Suppose you had a picture at 72 dpi, but very large--for example 27 inches wide. If you changed the resolution to 300 dpi, and then shrunk the picture to three inches wide--does the resulting picture end up sufficiently high resolution for printing?

jmarkbyrnes
12-30-2010, 08:23 AM
You can never actually add dots per inch to a photo. You can't put something there that doesn't exist.

But, if the image is 27 inches square or something like that, you should just scale the size down and it should still print decent enough; not good enough to put in a frame and hang on a wall, but good enough for a photo album.

Source: My wife, a graphic designer who lives in photoshop and illustrator 8 hours a day.

-papaholmz

DavidZahir
12-30-2010, 08:25 AM
Thank you.

LBlankenship
12-30-2010, 04:54 PM
Printing standard is 300 dpi.

Suppose you had a picture at 72 dpi, but very large--for example 27 inches wide. If you changed the resolution to 300 dpi, and then shrunk the picture to three inches wide--does the resulting picture end up sufficiently high resolution for printing?

It's all about the total number of dots. If your image has 72 dpi and is 27 inches wide, then your picture is 1944 dots wide. At 300 dpi, that will be 6.48 inches wide. That is plenty for most printing situations.

But be careful if you are messing around with resolution vs. size in Photoshop. They can be manipulated separately, but in many ways it's a good idea to think of them as the same thing.

WEM
12-31-2010, 04:18 PM
Printing standard is 300 dpi.

Suppose you had a picture at 72 dpi, but very large--for example 27 inches wide. If you changed the resolution to 300 dpi, and then shrunk the picture to three inches wide--does the resulting picture end up sufficiently high resolution for printing?

Carlavii just beat me to it. I was going to say the same.

But, if you have Photoshop, you can change the image resolution with resampling to image. Then when you print, it should scale properly for the printer.

I would not try to resize the iamge - it can be done, but doesn't add any detail.

jmarkbyrnes
12-31-2010, 08:23 PM
but doesn't add any detail.

You can't add detail to an image when the detail doesn't exist. Photoshop can't create pixels with distinct information out of thin air.

http://www.espressographics.com/text/imagesize.html


When the Resample Image box is checked, any changes you make to an image’s width or height will not change the image’s resolution, and as such, any changes you make to an image’s resolution will not affect the image’s width and height. Keep in mind, however, when you increase width and height, or resolution, with the Resample Image box checked, you are adding pixels to your image. These pixels don’t actually exist so Photoshop must create them. As such, you will succeed only in degrading the quality of your image.

Also,

http://graphicssoft.about.com/cs/resolution/a/increasingres.htm


Resizing an image using resampling, however, involves changing the pixel dimensions and will always introduce a loss in quality. That's because resampling uses a process called interpolation for increasing the size of an image. The interpolation process estimates the values of the pixels the software needs to create based on the existing pixels in the image. Resampling via interpolation results in serious blurring of the resized image, especially in areas where there are sharp lines and distinct changes in color.

When dealing with a digital image, you can never add detail. Instead, just about everything you do to the image will take detail away, in some way. So, once again, the best thing to do is just scale the size down and keep the same resolution. This option doesn't create any useless pixels that degrade your image further.

-papaholmz

PS - My wife made me post this; "adding detail" to a digital image using resampling is one of her hot buttons :)