Abery Clark
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.tiff resizing question
Let's say I take the original sized camera file (very big) and save it as .tiff. I take the original sized file (now a .tiff) resize (for the sake of this question) to 8 x10. Lest's assume the size will come out perfect for this example....no cropping...just resize in PS. After I resize, I hit SAVE (not save as). I want to go back later and make a larger print....lets say 16 x 20. I open the .tiff file (now saved as an 8x10) and resize UP to the larger size. Now my question:
Will I lose any MORE quality resizing (to larger size) the .tiff file saved as an 8 x10 than if I kept original camera size as master an "saved as" for each size needed. Since .tiff is uncompressed does it retain all data at every size?
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14/Mar/07, 4:32 pm
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crimbo
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Re: .tiff resizing question
Okay...when you up-size, the process guesses what to add in. Different algorithms claim to be better than others but in reality they are all guessing at what to add in.
The best file you will ever get is the original so if you intend to up-size you should keep a copy of that. Up-size that and then process it.
Also consider how the large print is being printed...your 10x8 is usually at 300dpi but as the print gets larger some printers drop this dpi so you may not have to add in as much data as you would if you stayed with 300dpi.
Also do not rely on theory do some experiments with your files and the printer you will be using until you are happy with the print.
An 8x10 at 300 dpi is around 7 megapixels
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Chris
60N
1W
http://www.paddle.shetland.co.uk
http://www.paddle.shetland.co.uk/my%20piccys/index.htm
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14/Mar/07, 6:12 pm
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Abery Clark
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Re: .tiff resizing question
So even a .tff file loses some data when downsizing.
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15/Mar/07, 4:31 am
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crimbo
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Re: .tiff resizing question
If you down-size you throw away data.
.tiff is lossless in the way it stores the data.
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Chris
60N
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http://www.paddle.shetland.co.uk
http://www.paddle.shetland.co.uk/my%20piccys/index.htm
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15/Mar/07, 7:03 am
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jfrancho
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Re: .tiff resizing question
There are two concepts to comprehend here. Resolution and Compression. They both contribute to overall file size and image quality, but in very different ways.
One other element at play is format. TIFF is a format that uses "lossless" compression, and is good for saving images as master files or works in progress, since multiple saves and save as' won't degrade image quality.
JPEG uses lossy compression, though saving as a high quality JPEG has no effect on image quality if done once or twice. It is best reserved for the last step in your work flow, before sending the file to the printer or posting on the web.
If you stick to TIFF (or PSD) throughout the editing process, compression becomes a non issue.
The next concept is resolution. When you downsize an image, it is important to consider the resampling method. Conventional wisdom says using bicubic sharper for down sizing images, and bicubic smoother for upsizing images is the best way to go. It really depends on hte image, and whether you will be sharpening the image after the resize.
Whenever you resize, it is always preferable to start with the original native resolution. For this reason, it is important that you save a "master" archive image file as a starting point for resizing for print or for web presentation.
Taking a full res image, and resampling it to 1200x1800 px. for a 300ppi 4x6" print will only really be good for making a 4x6 print. Especially if you consider that you probably used bicubic sharper for the resize and possibly sharpened it some more for printing. Sharpening is an inherently destructive process, and anything more than just removing the moire after raw conversion can degrade the image quality if done too much, at different sizes.
If you then want to print a 5x7" or 8x10", then you'll want to return to the "master" archive file, and resize from there. keeping track of these versions can get sketchy, but I like to use self explanatory folder names, like "print_8x10", or "web_800x533". This also works well with the lab I work with, as their FTP service uses the same nomenclature for folders.
A less complicated analogy using pizza dough works well. Say you have enough dough to make a 12" pizza. But you want to make a 9" pizza, so you cut a chunk of dough out, and throw it out. But then you change your mind, and really wanted a 12" pizza. You can stretch dough out and get a 12" crust, but it will be thinner. If you equate crust thickness to image quality, the analogy should become clear.
For more on resizing and sharpening, please see my anatomy of product shoot thread.
Last edited by jfrancho, 18/Mar/07, 7:53 pm
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18/Mar/07, 7:49 pm
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