no doubt a dumb resolution ? but i'm asking it anyway

[jann1033]

i have my camera set on largest finest jpg so i should be roughly 8mp( rebel xt) but when i download my pic they are 3456x2304 mp with a resolution of 72...
to get a 300 resolution for a print that means the biggest i could print would be roughly 11x7 ( according to the image resize in photoshop e5) which i thought was lots smaller than what 8 mp should print...

so is something set wrong somewhere along the way or is that normal?

what resolution do you find it best to print at?i thought between 200-300 but that means i could never print a 16x20 according to the photoshop setting, 200 is roughly 15 x11... (which i have done although i'm not crazy about the way it turned out,) 11X14 turns out great though which according to the above it shouldn't. or would my untrained eye not notice the difference between 2 and 3 /00 resolution

would raw help any towards giving me better resolution? (larger file to start with)

and if i crop a picture for say 8x10 i could never make that copy bigger right? it would have to resample is which i am thinking is not a good thing?

 

[ukcatfan]

I am not positive, but I believe that this is not something that you need to worry about. It is just the way the camera stores the information. I believe that the program doing the printing adjusts the DPI to the proper level accordign to the size of the print. Following that logic, the larger the print, the smaller the DPI. You can stretch a 1MP image to billboard size if you want. The DPI would just be very low.

Kevin

 

[boBQuincy]

Not a dumb question at all, in fact it is one that shows you are thinking about the whole process.
True, we should print at 300ppi for best quality, also true your camera's max resolution then comes out to about 11 x 7. What works for a larger print is to resample the image. Bicubic is one of the better resizing algorithms and is the one I use to print 13 x 19 and larger.

The whole resizing process is often called "ressing up" and there are some algorithms that are supposed to be better than the ones included with Photoshop, such as "stairstep" and "genuine fractals". Some people swear by them, some say they are worthless. I am in the middle and see *some* difference on *some* images but not anything consistent or that I would spend money for.

Keep questioning!

 

[jann1033]

Keep questioning!

you may regret the above

so then the missing manual book said to uncheck the resampleing box on the image resizer...i should check it again for certain sizes then? ie over the 11x7 or whatever it has for the resolution i want or should i just ignore the book and just leave it checked period?
thanks

 

[extreme8]

It's my understanding that you want to keep Resample unchecked as long as you're not trying to make your image any larger. If you're just changing resolution and not trying to enlarge the picture resample off is the way to go.
If you have the resolution set where you want it (300 ppi in your case) and your picture is only 11 x 7 you will be forced to resample in order to make it any larger.
You can just turn on resampling, set the resolution and size to what you want and click OK, but you take your chances on quality. I've started using "Bicubic Sharper" if I need a larger print size, but I don't know if that is available in Elements.

The best solution I've seen is the new Blowup software from Alien Skin.http://www.alienskin.com/blowup/index.html
I swear, the upsized images are indistinguishable from the originals in nearly every test I've performed.
Some kind of advanced fractal voodoo.

 

[jann1033]

thanks for the link extreme8 and the help from all

 

[extreme8]

OK, your question got me wondering.
I went and found an image of mine with interesting detail and tried a few different ways of enlarging it so I could compare the results.

This is the method I used-
I took a 6mp 72ppi image at full full size straight out of my old Minolta 5D - it produced a picture at 72ppi, 27.778" high x 41.778" wide. Big, but low res.

As Jann already knows simply bumping the resolution to 300ppi gives you a print size of 6.5" x 10". High res, but tiny.

What we need is a big, high res version for our printing, so this is what I tried;
My goal was a 20" x 30" print at 300ppi. I don't expect to print that size very often, but as long as we're shooting for the moon lets see what kind of quality we can retain.

The Jpeg used for this test had no sharpening applied. I expect I could extract a little more quality, but since this is test of resampling techniques and not my photoshop skills I decided to just leave it alone.

I then tried 4 different methods of converting to 300ppi @ 20 x 30
Just setting the crop tool to 300, 20x30 and selecting the whole image, Bicubic, Bicubic sharper, and Alien Skin Blowup.
It appears that the crop tool uses the default Bicubic resampling technique so I tossed out those results.

Final decision -
Bicubic and Bicubic Sharper appear to have almost identical quality. I couldn't see a difference at this size. Maybe if we bumped it up to 40 x 60 the differences would be more apparent, but for day to day use it's a total tossup.
As expected Alien Skin was sharper than the others. In this test it was marginal, but in some others I tried (and naturally neglected to save captures of) the difference was quite noticable - Edges are sharper and less noise, no pixelation on edges.

bottom line - any of the methods would produce an acceptable 20x30 image but I think Blow Up is noticably sharper.

I've posted a closeup crop of my test subject here
http://www.flickr.com/photos/bpantani/
make sure to view them in the original size for the most detail.
If you download the originals and load them into different layers of the same document you'll be able to compare them by switching the layer visibility on and off.
Remeber these were reduced to 75ppi and jpeg'd, so some loss has occured.

 

[boBQuincy]

OK, your question got me wondering.
I went and found an image of mine with interesting detail and tried a few different ways of enlarging it so I could compare the results.

This is good stuff, real testing with real data!
To muddy the waters further, Fred Miranda (and others) has some resampling and sharpening routines that appear to do better than the stock Photoshop routines.

I am sure the algorithms will only continue to get better. To me this is one of the compelling reasons to use RAW, so as better software is available we can go back and redo our original images.
I re-converted an image I took with a Canon D30 about 5 years ago, and it was better than ever.

 

[Groucho]

The best resolution to print depends on your printer. Some work best at different DPI levels - generally the higher the better, but at the expense of time and ink. We have two printers - a b/w laser and a cheap Epson color inkjet. The laser wants to print at 600, the Epson wants to print at 360.

As usual, Irfanview has a nice, powerful printing system, allowing you to print at the photo's indicated DPI or set your own (or any of a number of different options.) That's what I use when I'm going to print something (which is fairly rare.) I never bother resizing the photo ahead of time, I would think that the real-world different will be pretty difficult to notice, whether it's resized ahead of time or while printing.

If you're taking a poster-sized document to a professional print shop, that's another matter, of course.

Back on enlarging - if you really want to be exhaustive, Irfanview also lets you choose from six different methods of resampling: Lanczos, B-spline, bell, Mitchell, triangle, and hermite, listed from slowest to fastest. Lanczos seems to generally produce very good results. In addition, it has plain old resizing, which looks the worst as there's no attempt as smoothing out the results jaggies.

 

[jann1033]

i downloaded and tried the free alien skin demo and i couldn't tell much difference between the re sized at 300 and the one that came out of my camera at 72 which is i am thinking a good thing ( ie didn't loose anything by resizing) i could clearly see the spots on the butterfly's antennae so to me that is sharp enough i posted it on the macro thread but it's smaller than real life and harder to see and i don't remember which i ended up posting all of which proves i'm not nearly as organized as extreme8

 

[seashoreCM]

1. It is best to take the pictures with the maximum resolution your camera has, for example 3456x2304 for some 8 megapixel models. A possible exception is if you are concerned about running out of space on your camera memory card and cannot easly buy another memory card for continued picture taking in which case you have to choose a lower resolution.

2. Don't worry about the resolution number such as 72 or 300. Just decide on the final print size you want. If print size is chosen only using resolution numbers and not inches, you would have to use trial and error, a table in the instruction manual, or your own calculations to get the pirnt size right. Pixels high for the downloaded image divided by the print's resolution number in dpi equals the final picture hight in inches. For example an image 2304 pixels high printed using 300 dpi should deliver a print about 7-3/4 inches high.

2a. If you get to choose both the print size in inches and the resolution in dpi, most likely this means the resolution number selection specifies the theoretical print size in inches using the above calculations while the inches selection crops the picture to the final size specified. There must be additional numbers to choose to specify what part of the picture (top left, center, etc.) you want to keep.

2b. To view the image on your computer monitor with a 1 for 1 pixel match, that is, 100 x 100 pixels worth of photograph occupy 100 x 100 pixels worth of monitor screen, you choose a resolution number around 72 dpi. Check the instructions of the viewing software to get the exact number. The actual size of a 72 x 72 block of pixels will vary with the monitor screen size. Don't forget that if you downloaded images with different resolutions such as from different cameras, a 100 x 100 block of pixels represents a greater percentage of the area of a lower resolution image compared with a higher resolution image.

Disney hints:
http://members.aol.com/ajaynejr/disney.htm