Save image pixel problem?

Frank · Post by **Frank** » Wed May 28, 2008 1:39 am

You are correct, ... I have no problem printing the image ... It prints out at 8.5 x 11.7 with great quality .... Also viewing the image on a large scale is fine .... It was just applying the other apps that gave me the problem ..... Again, thanks for your time with this matter .....

fortemac · Post by **fortemac** » Wed May 28, 2008 1:10 pm

It also does this on any created from scratch page--other programs are not able to read all the extra data of the image. I understand that the pixel by pixel size is exactly the same when it is opened in all programs; however, the size the image is read changes significantly because other programs read all images created in PI 12 or PI X3 as the default 72dpi. When my art is quality-checked before releasing to the store, others don't see that the pixel by pixel size is the same whether it is a 72 or 300 dpi project. They just think I messed up and think I designed a page at 50 x 50 inches instead of 12 x 12.

I was able to get around this by saving my art using the File Command--More Save Options, Save for Web, Save Entire Image. Only then is all the extra data saved (other than just the pixel by pixel size). It does change the size. I think it may be compressing it due to it being an Image Optimizer--which may not be good for me. I'll have to test it on a few images and compare them. If it does work then I will add a button to my customized tool bar for a quick save.

I'm back--
OK this will only work on jpegs (I should have guessed as it was for web). Any png image cannot be saved this way so I will continue to have to open the Adobe program to re-save my images. I must have other programs to recognize the correct size by inches. I also create art for crafters. Crafter-types need to know what size an image will print (before it is printed) so that they can glue the paper to other objects. They cannot guess or waste money printing a page out to see what the size is. They are confused when an 8.5 x 11 page of art says it is to be printed on paper that is 35.417 x 45.833 (that's what a PI designed page says in other programs). It's a lot of extra work for me to re-save it in Adobe, but it's better than having to deal with questions about my designing skills.
Cyndy

Post by **Ron P.** » Wed May 28, 2008 2:45 pm

I think it has less to do with your designing skills, and more to do with the extreme confusion of DPI. I don't care what program is being used on a PC or Mac, DPI means nothing to them, only PPI.

Those that want to say that you're not creating the artwork to specs, are well simply put arrogant and ignorant

Ignorant of what the DPI measurement is really used for, and arrogant for refusing to educate themselves... JMHO..

Frank · Post by **Frank** » Wed May 28, 2008 5:33 pm

Ok .... I thought the term dpi stood for Dots Per Inch ... Is that correct? and ppi stands for Pixels Per Inch .... Is that correct? .... If these assumptions on my part are correct, What is the difference between the two? ...... I understand that neither one of these has an effect on the actual image, but it does have an effect on the size and quality of the printed or viewed image. As an example, you can liken it to an accordion, compressed it¡¦s appearance is relatively a cube, but once extended it¡¦s a rectangular box. Either way, all the parts of the accordion are still there, they¡¦re just spread out more. This is, to me, what appears to be happening when the dpi/ppi (resolution) information is changed in the properties of the file, making it appear larger than it is. The thing is PI 12 isn¡¦t noticing the difference whereas other apps are ¡K¡K

Post by **Ron P.** » Wed May 28, 2008 5:47 pm

DPI (dots per inch) is used for print (paper) media only. A screen, computer monitor or TV has no idea on what to do with these dimensions. A printer however does, and uses it.
PPI (pixels per inch) is what display media (pc monitors and TVs) recognize and use.

Do a Google search for DPI vs PPI and you'll get some good reading, and explanations.

Frank · Post by **Frank** » Wed May 28, 2008 6:21 pm

Great page - http://www.tildefrugal.net/photo/dpi.php ... Thanks for the info ...

njdowding · Post by **njdowding** » Wed May 28, 2008 10:43 pm

Maybe this will also help.

As his been said here in many ways the only thing relevant to an image on a computer screen is how many pixels it contains. If you have an image 1024 x 768 pixels and your screen resolution is set to 1024 x 768 then that image viewed at 100% fills the screen. Inches cm etc have no relevance.

If you want to scan in or print out then dots per inch or pixels per inch become the control as to how big the image is printed out or how many pixels your image contains when you scan in.

Take scanning. Scan a 4"x4" image and scan at 600 dpi or ppi then you get an image 4x600 pixels wide and high.

Open this in PI (this is the bit that seems to have caused confusion here) and the reported size will be 2400 pixels by 2400 pixels.

Lets say it shows a resolution of 300 ppi, the active image resolution will show as 300 ppi. This will give a document size of 8"x8" as a result. Now unclick resample so you make no physical changes to your image and change the resolution to 600 ppi. Now the document size reverts to 4"x4" as scanned. No change has been made to the original image, the pixel count is still the same. You are just saying when I output this use 600 of my pixels per inch. If you have resample checked however you will alter the pixel count when you change resolution hence you loose quality.

Close the resize dialogue and reopen and now the image will still be reported as 2400x2400 pixels but with a resolution of 600 ppi.

So in summary divorce physical size and pixel count. Do not use resample when changing resolution.

Edited : You are right it is metadata not software, Thanks.

HTH the discussion.

Nick

John Moran_2 · Post by **John Moran_2** » Wed May 28, 2008 11:18 pm

If I recall correctly,

Maximum Pixel count for 16 bit Photo Editors (Win3.1 - Win Vista OS)
•Max Pixel canvas ~32,768x32,768 pixels (limited by operating system)
•PhotoImpact canvas ~32,000x32,000 pixels (clipped by Ulead)
•Photoshop 16 bit canvas ~30,000x30,000 pixels (clipped by Adobe)

Max size 16 bit PDF @ ~150 dpi (ppi) resolution
•Length 200x200 inches (limited by OS, clipped a little more by Adobe)
• Max Resolution for 200x200" PDF (32.768 pixels/200"= 163x163 ppi)

Whether a printer manufacturer calls a dot a pixel, or a pixel a dot, or prints in 12 colors, the limit is still 32,768x32,768 (dot~pixels) per 16 bit image. Manufaturers advertisements may do funny things with the numbers, but the computer and the operating system cannot. (A special printer diriver, called a RIP, could of course work around this)

Whether a Photo Editor application has a built in utility for calculating pixel count vs paper size, and/or displays rulers for the user's convenience, or not, the printer driver has the final say.

FWIW, If I recall correctly, your mileage may vary, mine usually does.
JM_2