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Posted on 15/05/13 10:58:57 AM |
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Mariner
Renaissance Mariner Posts: 3007 Reply  |
Image Size Command Options - do they really make any difference?
The Image Size command options are, among others, Bicubic Smoother (best for enlargement) and Bicubic Sharper (best for reduction). For years I have exclusively used these two, without giving it a thought. Today I decided to try a little test. I opened Image A and saved it as Image B then closed Image A again. I now have two identical images on my hard disk, Image A and Image B. (They don't call me Genius for nothing, you know). Now, each of these jpegs was 21cm x 21cm and 200 ppi. So I loaded Image A and reduced its dimensions to 10cm x 10cm and saved it using Bicubic Sharper. Then I opened Image B, reduced it to 10cm x 10cm and saved it using Bicubic SMOOTHER. If I load both reduced images into one file and blend them together using Difference, I should be able to see the difference between them, right? There was no difference. At least, not using this method. Can anyone advise me on this? |
Posted on 15/05/13 6:55:54 PM |
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Deborah Morley
Makeover Magician Posts: 1319 Reply  |
Re: Image Size Command Options - do they really make any difference?
Hi, I must admit I tend to use the automatic option. But I have just tried reducing an image (psd not jpeg) not sure if that would make a difference; and when comparing the two images; rather than blending them, there was a big difference. Why blend them together using Difference? Only curious.  |
Posted on 15/05/13 8:08:50 PM |
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vibeke
Kreative Kiwi Posts: 2166 Reply  |
Re: Image Size Command Options - do they really make any difference?
Deborah, definitely quite a difference there, I will take more care in the future at what I select. I just checked my settings and see I normally use Bicubic smoother. _________________ Perfect confidence is granted to the less talented as a consolation prize. |
Posted on 16/05/13 01:52:52 AM |
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Mark Goodwin
**** Posts: 261 Reply  |
Re: Image Size Command Options - do they really make any difference?
I can't remember where I read it (it would have been either Steve or Scott Kelby) but mine is always left at Bicubic automatic. I must say that I have appeared to have not had any probs as yet with either up or down sizing. However, there is a tremendous difference in Deborah's example. _________________ Mark Goodwin If you do what you have always done, you'll get what you've always got! |
Posted on 16/05/13 07:12:52 AM |
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Mariner
Renaissance Mariner Posts: 3007 Reply |
Re: Image Size Command Options - do they really make any difference?
Thankyou Deborah, Vibeke and Mark for your replies. Deborah, I based my experiment on a quote from Martin Evening's book "Photoshop for Photographers" where he states "An analytical application of the Difference is to do a pin register sandwich of two near identical images to detect any image changes - such as a comparison of two images in different RGB color spaces, for example." Now, I don't know what a pin register sandwich is, but I get the general idea. Anyway, the result was pure black. Even when I zoomed in really close it was still all black. So much for that then. Back to the drawing board. Thankyou all. |
Posted on 16/05/13 07:52:06 AM |
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Steve Caplin
Administrator Posts: 6997 Reply  |
Re: Image Size Command Options - do they really make any difference?
Photoshop CC now has live previews in the Image Size dialog, as well as a Noise Reduction slider when enlarging images. By switching between the different methods, you really can see a difference between the methods. |
Posted on 16/05/13 08:52:42 AM |
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Sjef
Flying Dutchman Posts: 571 Reply  |
Re: Image Size Command Options - do they really make any difference?
Deborah's post is a fine example of the way Photoshop crops images. This option annoys me a little, because it doesn't 'remember' the way I like my photographs to be reduced in size. I mostly keep the originals of my photo's (12 Mp) and often enhance some of them in Photoshop after which I crop them to my screen resolution 1200 px in height). Using sharper or automatic my photo's get too sharp. The edges are fringed. See the arrow in the attachment. So I always use Best for smooth gradients. To Dodge/Burn the pixels to a point as in Automatic I use Contrast. I wouldn't know if there should be something to see in the Blending mode Difference. I've tried but it's getting black. This is about jpeg and not about raw. (Click on the image to get 100%) 
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Posted on 16/05/13 11:05:25 AM |
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Mariner
Renaissance Mariner Posts: 3007 Reply |
Re: Image Size Command Options - do they really make any difference?
Thankyou Steve, Sjef, for your replies. |