View Full Version : Maybe if you gave me a trail of breadcrumbs


CascoGraFX
12-01-2004, 08:59 AM
Although RonDon and many of you have tried, I just cannot fathom the resampling:resizing:dpi:ppi:scanning "connection". Just when I think I've got it......I don't have it. Just this morning I figured out (alright, my wife gave me the idea) a way to understand this. I am "using" Photoshop and Image Ready CS (I also have Genuine Fractals and a host of other filters and plugins), an Epson 3.3 Megapixel digital camers and an HP Scanjet 4470c.

I have a thumbnail photo of a red clay plantpot - just the standard, straight-sided, tapered plant pot shape - at a resolution of 72 ppi. The thumbnail measures 1" x 1 1/2". I used the plantpot example because of the clean edges and straight lines. I want to make this into a 5x7 with the same clarity as the thumbnail (although I have no idea why) and I guess it all boils down to 2 questions?

1. Can this be done with my present hardware and software?
2. If it can be done, is there a tutorial on the site (or elswhere) that addresses tutorials to old guys with too much time on there hands?

Thank you all so very much for your patience and kindness and have a wonderful Holiday Season.

ExclamPt
12-01-2004, 09:31 AM
This discussion will include mention of resampling. I have attached a picture which may help by showing the effects of resampling to decrease and to increase resolution respectively.

I hope this helps.

Doug Nelson
12-01-2004, 10:55 AM
Perhaps you can think of it this way:

Take the total number of pixels wide and tall and divide that by the final output inches wide and tall. That will tell you how many pixels are actually getting printed per inch of final output. This removes both PPI and DPI from the equation, since you can print at 72 or 4800 DPI and it won't change the number of available pixels in your file. Anything less than 150 image pixels per output inch will give visible pixelization (squares). There are tricks and software to blur the pixelization (squares), but they don't actually do anything else (no matter what rocket science they throw at you in the marketing materials).

So in your example you'd have 72 pixels by 108 pixels to spread over 5 inches by 7 inches. It's a safe bet this is less than 150 pixels per output inch :) No matter what you do to the file or the printer, no matter what software you buy, this is all the information you have to work with.

So here's your breadcrumbs:

1. No
2. No

byRo
12-02-2004, 05:09 AM
1. No
2. No
Thinking inside the lines, I would agree.

However....

Certainly without realizing it CascoGraFX posed a trick question:

I used the plantpot example because of the clean edges and straight lines.
That information is NOT strictly evident from the thumb-nail shot. Although he stated it explicitly, this is something that we all know from the moment that we recognize that the image is of a plantpot.
I want to make this into a 5x7 with the same clarity as the thumbnail
Strictly speaking, again: If you enlarge the image by an integer multiple using "Nearest Neighbor" (and not "Bicubic"), you have exactly the same image (information) as before - just bigger. It doesn't look good because you're expecting to see confirmed the "clean edges and straight lines" information that was in your head and not in the image.

That said, I could manually add the information to the thumbnail image in the form of a set of vector masks tracing the (in-my-head) "lines", and then resize. Being vectors, these straight lines are unaffected and I could use these to manually, again, clean up the image.

In resume:
1. No*
2. No*
*see post above.

Vikki
12-02-2004, 08:57 PM
There are some people that have tried different methods to achieve you're goal, but none that I know of have managed to achieve quality results.
Trying to decipher all the resolution stuff is a problem for many people. Here's another way to look at it.
http://www.retouchpro.com/forums/attachment.php?attachmentid=14682

CascoGraFX
12-03-2004, 07:23 AM
Thanks to all of you, I now understand the way everything works (and have printed the "graphics" which you so thoughtfully provided). The two examples are on my bulletin board right in front of me lest I have a momentary lapse! Thank all of you again for your support.