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Input/Output/Workflow Scanning, printing, color management, and discussing best practices for control and repeatability

Scanning for Enlargements

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  #11  
Old 08-18-2001, 11:47 PM
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does that mean when you go to the image size box and put in your new larger dimensions, you leave the res. box unchanged? no touchy?
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  #12  
Old 08-18-2001, 11:52 PM
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That's all interpolation, so really all it does is slow things down. No harm, no foul.

What I do is finish my restore, save, make a copy, and then resize that copy physically in PS to the paper size. This allows me to set the canvas size to the final print size and compose the image appropriately. This is also usually the first and only place I'll use USM.

I make my prints, then save as a flattened compressed TIF, in case they reorder.
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  #13  
Old 08-19-2001, 05:20 AM
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Doug,

I think I understood the question the same way you did. Would it be accurate to say that all pixels (not interpolated) should be thought of as having useable information, but that the quality of the enlargement would be directly related to the quality of the original, when enough optical resolution is used for enlargement? *Unsubstantial* losses such as Tom described can be disregarded (such as losses created from opening and closing a file).

Isn't interpolation when you increase the number of pixels in the image? If so, lowering the resolution (without resampling) would increase the *size* of the pixels, but not the *number* of pixels, thereby creating a larger print size without interpolation (although *unsubstantial* minor degradation might result). If I'm not clear on this, somebody needs to drill this into my thick head.

Tom,

I've heard about Genuine Fractals before. Some people say that you can *greatly* increase print size without noticeable loss when using this program. Just how good is it?

Ed
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  #14  
Old 08-19-2001, 07:50 AM
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Ed,

I'm not sure if I follow you or not, but I've got the drill ready...

It sounds like you're basically just saying increasing the size without resampling lowers the resolution, which is true. Less pixels per inch because the same pixels are spread further apart.
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  #15  
Old 08-19-2001, 08:48 AM
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Maybe I don't understand the concept correctly. Are you saying that there is void space between the pixels, or are the pixels becoming larger? I guess I'm not making it clear what my understanding (which may not be correct)of the process is. I'm thinking that when the same number of pixels covers more area (inches), the pixels actually become larger, and still border each other with no space between.

I think it was Debbie who suggested that if she didn't understand something, there are probably others who also don't understand it. So, rather than look stupid, I'll go along with that concept.

Ed
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  #16  
Old 08-19-2001, 10:33 AM
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The pixels touch. No void. It's just a numerical statement of the value at a given coordinate.

How many coordinates are used determines the resolution. If you enlarge using the same number of coordinates, that numerical value has to be spread to cover a larger area.

Interpolation looks at these 'coordinate values' and guesses what should fall between. The varying theories as to HOW it should guess make up all the different resampling schemes.

There's very little corelation between the number of pixels per inch in a file and the dots per inch a printer is capable of laying down. To ease the concept, assume the resolution of the printer is infinite and perfect (it isn't, of course, but we're talking theory here).

Imagine a 'pixelated' image. Big squares, jaggy diagonals. That's the coordinate values being spread to cover larger areas.
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  #17  
Old 08-19-2001, 11:17 AM
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Hi All--it looks like I've got everyone thinking here. Thanks for all your input.

A question for you Tom:

Quote:
Originally posted by thomasgeorge
Akj, Scanning at around 300 to 400 dpi will give you enough data to make a good 8x10 blow up from a 4x6 size. If you have around a 7 to 10 mb file size, after resampling, you should be OK.
Did you mean to say resampling? Or scaling? If you change the image size (with resample box unchecked) this will change the resolution but not the actual number of pixels (otherwise known as scaling). So shouldn't the file size stay the same before and after you've changed the dimensions? If you have the choice between resampling an image and scaling it--isn't it best to scale?

So, to touch on what Doug said--if I scan in an image at let's say 400 pixels--I scale the size up--and as long as the resolution is 150-200 dpi, I should be OK? And, like Ed said, the quality of the enlargement will depend entirely on the quality of the original. So, I guess the only way to judge whether an enlargement is satisfactory enough is to simply print it out and see? Should I not worry so much about "scan quality"?

Maybe I may be making this topic more complicated than necessary.

Amanda
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  #18  
Old 08-19-2001, 11:43 AM
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Doug,

I think what you are saying is exactly what I had in mind to begin with.

Amanda,

You are not making this thread too complicated. I think it got a lot of responses because of the way posts were worded and/or interpreted. (Hope this doesn't start another one)

Ed
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  #19  
Old 08-19-2001, 11:55 AM
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Akj, You are right. Poor choice of words on my part. I was refering to upsampling which can be either fixed or variable resolution type. Sorry! With fixed resolution type the file size increases. With variable type the the file size,actually the number of pixels, is unchanged. Tom
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  #20  
Old 08-19-2001, 12:05 PM
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Ed, the program Genuine Fractals from Altimira is useful if you do alot of enlarging or compositing work as you can scan or otherwise import an image at a relatively small size then upsample or down sample it as your needs dictate without having to have multiple images at different sizes stored on your hard drive eating up valuable storage space. Unless you do lots of that sort of stuff where the work must undergo some pretty radical changes, it probably isnt a necessary "plug in" to aquire. I only use it a couple of times a month if even that but when you need it its nice to have. It works well, but keep in mind that VIEWING DISTANCE enters into the equation as well. An enlarged image viewed from say 2 feet is going to look better than the same one viewed from 6 inches. The bigger the finished image the more "fuzz etc " there may be, and Fractals cant compensate for a borderline original image.If its fuzzy or otherwise less than perfect, so it will be after fractals finishes its work. Tom
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