Working with digital images

[brevityrecords]

Hello -
I recently purchased a Kodak DX7590.  I have a question regarding ppi & resampling.  Please read on.  
I  took a landscape picture at the highest setting (5.0 megapixels) and opened the file directly from the SD card into Photoshop.

In Photoshop when I check "image size" the following is displayed:
Pixel Dimensions:14.3M; Width: 2576 Pixels Height: 1932 Pixels.; Document Size: 35.778W inches x 26.833H inches.  Resolution is 72 pixels/inch.

I want to print the photo as an 11 x 14, so I enter 14 into Width and let photoshop Constrain Proportions. It populates 10.5 into Height,  1008 pixels Width x 756 pixel Height.  Still at 72 PPI.  (good enough for this example).

My big question is:  Will this resolution print a nice sharp print?  OR do I need to RESAMPLE the image to 300 PPI (which the photo lab I take to can handle) If I resample am I getting any benefit from doing this?

I WANT PROFESSIONAL QUALITY RESULTS!  I am confused, because a friend of mine has the 4.0 mega pixel version of the camera and when opened directly in photoshop the PPI is above 200.  Mine comes in at 72 PPI, which in my opinion is only good for Web applications.  

I can't seem to find a way to get a higher PPI direclty from the camera.  I even switched to "fine" JPG compression & it's the same when I bring them into photoshop.  I typically take the shots from my SD card, manipulate them (Contrast, color, crop etc.) then take them to get printed as enlargements.  I want to maintain the ability to manipulate in Photoshop and save the files and get them printed.  I know a lot of labs have color balancing, cropping etc, but I want to maintain that control!

Thanks in advance!  If this sounds confusing...it is for me also!

[ShutterbugGail]

Hi brevityrecords,

Welcome to Digicamhelp!

As far as I know, digital cameras do not have a setting to change the pixels per inch. Some digital cameras have other options, such as to create a TIFF or RAW file.

One of my digital cameras creates images at 300 ppi. Another camera I have creates images at 72 ppi. I see no difference in the print quality. Remember too that jpegs are compressed, so when you open them in image editing software, they uncompress. For example, when I right click on an image the file size is 618K. When I open it in Photoshop and check the size it is 5.49M.

The main issue your camera's megapixel count. Though opinions differ, generally a five megapixel camera is said the have the optimal printing results for an 8x10" print. Six megapixels are recommended for an 11x14"
print. Depending on the image, I think you should be able to get a very good quality.

Take a look at Photoshop's help files. They contain lots of helpful information about getting the best print quality.

[ShutterbugGail]

Here's some of what the Photoshop says about Image resolution:

"The number of pixels displayed per unit of printed length in an image, usually measured in pixels per inch (ppi). In Photoshop, you can change the resolution of an image; in ImageReady, the resolution of an image is always 72 ppi. This is because the ImageReady application is tailored to creating images for online media, not print media.

"In Photoshop, image resolution and pixel dimensions are interdependent. The amount of detail in an image depends on its pixel dimensions, while the image resolution controls how much space the pixels are printed over. For example, you can modify an image's resolution without changing the actual pixel data in the image--all you change is the printed size of the image. However, if you want to maintain the same output dimensions, changing the image's resolution requires a change in the total number of pixels.

"When printed, an image with a high resolution contains more, and therefore smaller, pixels than an image with a low resolution. For example, a 1-by-1-inch image with a resolution of 72 ppi contains a total of 5184 pixels (72 pixels wide x 72 pixels high = 5184). The same 1-by-1-inch image with a resolution of 300 ppi contains a total of 90,000 pixels. Higher-resolution images usually reproduce more detail and subtler color transitions than lower-resolution images. However, increasing the resolution of a low-resolution image only spreads the original pixel information across a greater number of pixels; it rarely improves image quality.

"Using too low a resolution for a printed image results in pixelation--output with large, coarse-looking pixels. Using too high a resolution (pixels smaller than the output device can produce) increases the file size and slows the printing of the image; furthermore, the device will be unable to reproduce the extra detail provided by the higher resolution image."

[Deb]

Hi Brevityrecords,

Yep, resolution can be a bit tricky to get a handle on. Think of it as a sliding scale. For instance, you've noticed that your image (2576x1932 pixels) equates to 35.778W inches x 26.833H inches  if viewed on a monitor or printed at 72PPI. If you want to print at 300ppi (standard ppi for photographs), you'll see that your image now equates to 8.587W inches x 6.44H inches. (You can see for yourself by changing your ppi to 300ppi in IMAGE > RESIZE > IMAGE SIZE making sure "resample" is not checked. Now, you can still maintain photographic quality with ppi within the range of 240ppi and, in some case, lower. It depends on your output device. To get a roughly 14x11 print from your file without resampling, the resolution would be approximately 184ppi. If you wish to resample, that is, letting your software "create" additional pixels for you, select the "resample" box as well as the "contrain proportions" box and use the "bicubic" method. Set your ppi to 300ppi, your width to 14 inches.

The reason why Photoshop is opening the file at 72ppi is because you may not have a printer associated with it. If you have a printer associated with it, it could open the file at printer default resolution.

Oh, one other thing, if you want full resolution out of your camera, shoot in TIFF/or RAW mode. No compression is occurring in these modes. Compression discards pixels and they are recreated when it is uncompressed.  

Hope this helps.  

[brevityrecords]

Thanks for the info. Upon calling Kodaks so called  "customer support" there is no way to shoot uncompressed & the default of 72 ppi isn't changeable.  The Tier 2 support didnt even know what PPI was!!!  & it only took 50 minutes on hold most of the time to get this answer!  Frustrating!!!

Continuing the topic...
Now, if I hold to what Deb is saying about photographic results being above 240 PPI, the largest print I can get is an 8.05 x 10.733.  Going to the 10.5 x 14 produces 184 PPI.  I guess I can take the 184 PPI shot to the lab and see how it turns out.

If I resample the image to 10.5 x 14 at 300 DPI, photoshop will "create" pixels based on a mathmatical algorithm, but the quality wouldn't visibly increase any more than the 184 ppi right when printed at the lab?  I ddn't think it was possible to "increase quality" from the original source file by resampling.  Is this true or would I get noticably better prints by resampling?

I'm not worried about file size, which seems to be the only thing that increases when resampled at 300 PPI.

Why does Kodak boast a 20 x 30 "superb quality" print?  Is there something I'm missing here?  How can you get superb quality from 72 PPI?  Give me a break!

[Mike54]

Try checking out this link it might help.
Now, if you were to take your original image of 2576 x 1932 and crop it for an 11 x 14 print using as much of the original as possible you would have an image at 2460 x 1932. If you do the math you'll find that the ppi = 175 which IMHO should provide a perfectly acceptable image.

[Deb]

Dandy link, Mike!

Here's something else you might like to look into. It's a software called "Genuine Fractals" (http://www.lizardtech.com/products/gf/overview.php). A review can be found at http://www.imaging-resource.com/SOFT/GF/GF.HTM . Notice the "comparison images". These compare enlargements results of PS vs. GF.

I've played with the demo and it's fabulous!

[ShutterbugGail]

As you are learning, this area can be a pretty complicated aspect of digital photography. After all these years into digital photography and printing digital images and scans, I can't say that I completely "get it." I do know, however, that I've gotten some excellent quality prints from my cameras that produce images at 72 ppi.

The size you are able to print relates to megapixels and resolution. I'm not sure you can get a " 20 x 30 superb quality" print from a 5 mp camera but I do think you'll get a very fine one at 11 x 14." If you decide to give it a try, let us know the results.

[brevityrecords]

Hello -
I have taken the print to my developer and even though the resolution was at 170 ppi at 11 x 14, the resolution was really good.  Thanks to all for the help.

[ShutterbugGail]

Super! Thanks so much for coming back and sharing. It will help others and we appreciate it!