 Rita |
Adobe Photoshop, Resample Image I have another PS question. I work with both scanned and digital photos. When I change the sample size of my digital photo, do I check "Resample Image"? And if so, what do I select on the pull down menu? And what do I select when I am resizing a scanned photo? Thanks!
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doug Nelson |
The image/Image Size page lets you change the resolution and the dimensions of the image, IF you Uncheck Resample (always check "Constrain Proportions"). Use Resample ONLY if you are throwing out pixels, such as when downsizing an image so it can used on a web page. When you do this, always ask yourself if a Save As shouldn't be done to preserve the original size image. Resample is the chain saw of digital imaging; mess with it only if you know what you want. You can Resample in order to add pixels, to increase the file size. Do this rarely, if at all, because it never results in a better image, just a bigger file size. See if the articles on my web page are any help, and come back with any questions.
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Rita |
Thanks! So I only want to click Resample if I am downsizing for the web, or adding pixels (which I never do). But now I have a new question. My photos taken with my rebel are around 11 x 17 inches. I usually make a copy that is edited to print out as a 4x6. Do I crop with 4 x 6 inches selected in the crop tool in PS, and not check Resample? My file is still quite large in that case which takes it longer to upload to the photo place. Do I have to worry about losing resolution if I am only printing out a 4x6 print?
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doug Nelson |
Look at a full res shot from you Canon, right off the memory card. It's 17 x 11, but does the resolution read 72 ppi? Go into Image Size and enter 240 as you res and watch Photoshop do tthe calculation. You wil get a size at which you can print your image. Is even that size too large? Crop only if there's a part of the image you don't want. The pixels you throw away are gone forever. Instead, go to Image Size, Resample UNchecked, and enter 6 as your image length. You will get a readout on the resolution as a result. If the resolution is at least 240 pixels per inch, and even as much as 450 or so, go ahead and print it. As long a Resample is not checked, you lose NO image quality and throw away NO pixels. You are merely reshuffling them. If there's a problem with printing a file size this large, Resample it down so that your resolution reads 240-300 ppi, and the dimensions are 6 x 4. SAVE AS name of file,4x6, then print it. That way, you will always have the option of a 4x6 printable, AND an even bigger print later on (from your original file). Save the original file as file name,high res or whatever is convenient for you. You might consider uploading that small file to the photo place and burning your big files to CD ROM. Do yourself a favor. Go to scantips.com and read up on Unsharp Mask. It's the last step before you print a picture.
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Michael H. Cothran |
Rita - Here's another way (possibly simpler) to look at it: In the Image Size window - 1. When you have Resample Image UNchecked (and it doesn't matter whether Constrain Proportions is checked or unchecked), all three items - width, height, and resolution are linked together. If you change one, all three change proportionately. Use this, for example, when you want to see how much resolution (ppi) you'll have at another size, or if you want to change your image's dimensions without altering the file size, or adding interpolation. 2. When you have Resample Image checked, and Constrain Proportions UNchecked, then you can alter ANY of the three without affecting or changing the other two. You will introduce interpolation when you do this. Warning - if you try to change the proportions of your image, it will distort to some degree. A little may be ok, but too much will play havoc on its appearance. There is a much more appropriate way to do this. 3. When you have both Resample Image and Constrain Proportions checked, you have linked the width and height together, but not the resolution (ppi). With this, you can change the ppi at the size listed to increase or decrease resolution. Again, interpolation will be used. You can also do the contrary, and change one of the side's dimension, which will proportionately change the other side, but leave the resolution the way it is.
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Michael H. Cothran |
In response to your second question - anytime you are changing the proportions of your image you should use the cropping tool, not the image size window - otherwise you will distort your image to some degree. So if your proportion is going to remain the same, use the Image Size Window to resize. If your proportion is changing, use the Cropping Tool. If you're unsure about "proportions", email me at michaelhcothran@comcast.net, and I can walk you through it in a little more detail. Next (as you asked above), you've also got to figure out resolution, or ppi. Here's how to do this - First, SAVE your largest file with all your editing done to it as a "Master" file. Go to Image Size, and uncheck Resample. retype 4" into either the width or height, whichever it is for your image. Then, see what the resolution is. All you want to do is look. If it's above 300 ppi, then you're ok. You don't need a file size any bigger than 300ppi to print as your eyes will never see the difference, and the bigger size will only slow down your computer and printer. Now that you've verified that your ppi is greater than 300 you can go back to your cropping tool, type in your 4x6 sides, and type 300 in the resolution window. Then crop to your desire. Photoshop will, of course, throw away a lot of pixels here in order downsize for you, but that's ok. You've got your Master file saved, right?? Then you will want to add a little more unsharp masking to the new 4x6 file. If anything is confusing in this matter, I will glad to share with you what little knowledge I have. Just email me. Michael H. Cothran www.mhcphoto.net
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