Save image pixel problem?

[heinz-oz]

Any image in electronic form does not have a resolution, it only is a certain number of pixel wide by a certain number of pixels high.

Whatever other programs display it at has no bearing whatsoever on the actual image.

When scanning an image, the chosen ppi (pixel per inch) tells the scanner how many pixels to create for each inch of the scanned image.

Now opening this in PI with PI reporting the resolution as 72 dpi or in PS showing it as 600 dpi has absolutely no effect on the actual image. The only thing that changes is the actual physical size of the image when printed.

The problem arises because even so called experts constantly swap the terms dpi and ppi freely. That's where the confusion starts.

If you scan an image at 600 ppi and place it on another page which is not 600 ppi your scanned image comes out too big/small depending on the ppi used for the page.

Dpi (dots per inch) on the other hand only applies to a printer. Your home printer can place one dot of each base color, CMYK, into each pixel of your image, in other words, your image scanned at 600 ppi would have to be printed in 2400 dpi (4 dots in each pixel) to come out the same print size as the original. The image will print bigger than the original if the dpi is lower.

For 6 color photo printers the calculations are a bit different because the printer has more dots it can place in a pixel.

If you have to supply an image at 300 dpi you have to make sure that you have an image of 75 ppi resolution. Lets say your print should be 10 inch wide, you need an image of 750 pixels wide. This image will then print 10 inch wide at a print resolution of 300 dpi.

[Frank]

To heinz-oz ... I do understand what you're saying, but I believe you're not getting what I'm saying .... Because the properties are showing 72 dpi for the particular jpg that was edited and 600 dpi for the two (img008 & 9) that weren't, my software is seeing these as being different sizes ... If I open img011 with a different photo program, change the dpi setting back to 600, then remake the pdf, all images appear the same .... So therefore, the dpi setting makes a difference on my end for incorporating it with other jpg's in a set ...

[John Moran_2]

Adobe makes several programs, at least one of which creates a "virtual" printer file with a PDF extension. So it may be that while some users could be thinking they are still working in Adobe Photoshop, or Elements, or CS, they have actually "printed" a file using Adobe Distiller or equivalent.
JM_2

[heinz-oz]

To heinz-oz ... I do understand what you're saying, but I believe you're not getting what I'm saying .... Because the properties are showing 72 dpi for the particular jpg that was edited and 600 dpi for the two (img008 & 9) that weren't, my software is seeing these as being different sizes ... If I open img011 with a different photo program, change the dpi setting back to 600, then remake the pdf, all images appear the same .... So therefore, the dpi setting makes a difference on my end for incorporating it with other jpg's in a set ...

Ok, I hear what you are saying. Unfortunately I am unable to make you understand and that is my problem not yours.

It doesn't matter what the dpi reading is in PI or PhotoShop or any other image editor. What matters is the size in ppi if you want to combine two images. It has to be identical for the two since otherwise the dimensions will not correspond.

Let me try to rephrase the whole thing.

From what I can understand, you have an existing image (a page) with text and pictures. You want to add to this some other pictures and text which you scanned yourself. Am I right so far?

Now, the page (pdf file?) you are trying to put your scanned image onto is considerably less than 600 ppi, I'm sure. How big is that page in inches? Do you have an image of that page in PI as well ie. image 9 and image 10? If yes, what are the pixel dimensions of these images?

Let's clarify this before we continue.

[Frank]

Ok, Let¡¦s try this again, from the beginning ¡K. I¡¦m trying to make a searchable catalog of a Class Yearbook ¡K. Like the on-line pdf catalogs you see at auto part sites and such. It¡¦s a project for my brother¡¦s 35th class reunion. He thought it would be nice to put it on CD Rom or DVD Rom, depending on final size of the project, and hand them out to alumni. Since the yearbook is printed magazine style, scanning it in at 600 dpi allows for better removal of the Moire effect (checker boarding) you get from scanning items such as this. When scanning the yearbook, due to size constraints, every other page is scanned upside down and has to be rotated 180 degrees as well as some of the pages needing minor touch-ups due to the book¡¦s age. I was using Photoshop 7, which is now 6 years old, to do the repairs. A friend turned me on to PhotoImpact 12. Since I already use Ulead¡¦s VideoStudio, and like the program, I thought upgrading to PhotoImact would be good. There¡¦s a supplement to the yearbook consisting of about 20 pages, I figured I¡¦d start with that. I scanned all the pages in at 600 dpi, no problems. I opened every other page with PI 12 to rotate them the 180, then closed and saved each after they were rotated. The size readings of the jpg¡¦s shown, before and after the rotation, in the top of the window (5100x7019 example) never changed, so I thought nothing was done other than rotating it. I then opened Acrobat Pro to make the pdf, directed it to the 20 jpg¡¦s and let it do its work. I opened the resulting pdf file to find every other page as shown in my previous message, one large and one small. The larger pages were the ones I had rotated with PI 12. The first thing I did was try a different program (Nuance PDF Pro) (And please, you¡¦re a moderator, if you want to remove the other program names feel free, I¡¦m not promoting them, just letting you know how I arrived at the problem), and came up with the same result. It was then I noticed the dpi of the PI 12 jpg¡¦s were 72 and the untouched ones were 600. I opened each jpg that I rotated with PI 12 in PS7 and reset the dpi to 600. I used PS7 because when I opened them in PI 12 it showed them as already being at 600 (2nd posted pic). Then I retried making the pdf with both programs (Nuance & Acrobat) and everything was fine ¡K.. All I wanted to know is how to get PI 12 to save the pictures at their original 600 dpi. I posted jpg¡¦s of the settings for resolution I¡¦m using and was wondering that maybe I missed something ¡K¡K Believe me, I do understand all the things you are saying ¡K. I¡¦m an Architectural Engineer, have been for 20 years and I¡¦m pretty good when it comes to math and measurement ¡K.

[heinz-oz]

As I said before Frank, I consider it my problem not to be able to make you understand what I'm saying.

After reading your explanations above, the only thing I can think off is that you did something, maybe inadvertantly, when you rotated the pages.

I will try to reconstruct your experiences.

The fact of the matter remains that an electronic image does not have a resolution in dpi. Resolution does not come into it at all. The only times resolution has any effect on an image is when you scan it (the ppi resolution tells the scanner how many pixels to create for each inch of the original) and when printing (the dpi reolution tells the printer how many dots of ink to place into an inch of your image).

Please have a read of this article also http://scantips.com/. Maybe it will become clearer for you.

The only time an image will change size in PI is when you resize it with the "Resample" option selected.

Can you give me a step by step description of what you did to rotate the page in PI?

Thanks

[John Moran_2]

After a quick Google, one might consider the possibility that obsolescent PS7 is unable to read the 600ppi value embedded in jpegs by PhotoImpact 12, even if properly created. PS7 would then default to the obsolescent 80's Apple monitor resolution of 72 ppi. Most modern printer drivers and drugstore photo printers could and would overriide this in any event, but the introduction of Adobe Acrobat pdfs into the mix locks the 600/72ppi in stone. FWIW
JM_2

Edit: Upon further review, it is not clear to me that Ulead PhotoImpact, versions PI 12 or PI X3 actually embed "600 ppi" in the jpg file metadata. However it does seem to me that PI strips much of the existing Exif camera maker and user XMP/IPTC (Keyword, Caption) metadata from the file.

[Ron P.]

I think I see what Frank is seeing. I took the image that I used before, the one that the other programs read the resolution correctly, and rotated it in PIX3 (don't have PI-12 installed on this computer).

Prior to rotating, the image resolution was 600ppi. After rotating the resolution for some reason went to 72. I then changed it in the Adjust>Resolution settings back to 600, and saved it.

Opening the image in Corel PhotoPaint x4 the resolution was 72dpi, even though all the other dimensions were correct.

I will not have time until later in the day to further test this, but it would seem that PI is not maintaining some information in the file, or other programs just can not read it correctly. Opening the same file in PI again, the 600ppi resolution is read.. Very strange behavior..

[heinz-oz]

Well, I just did a test as well in PI X3.

I scanned a small page with 600 ppi and saved it. Rotated it physically (in the scanner) and scanned it again with exactly the same sttings.

Both images opened in PI show a resolution of 600 ppi. After rotation of the one page and saving it again, PI still reports the resolution as 600 ppi.

I still don't understand what all the fuss is about because this reading has no bearing on the image at all. The pixel size is still the same and that is the only measurement that counts.





Just click on the thumb nail to show a larger image.

[John Moran_2]

I just took a camera jpg from a Canon A-75 point and shoot, with exif resolution of 180ppi and rotated it in PI X3. Then Saved As with a different name.

When opened in Irfanview 4.10, both images still show a printer resolution of 180x180 ppi, but the rotated jpg shows exif resolution of 72 ppi, not the original 180ppi. It would seem that, indeed, PI X3 is changing the exif field to 72 dpi on rotated jpgs.

PhotoImpact's display of camera maker's exif data is incomplete, so the change is not obvious. Now to look in Corel MediaOne. Yes, in MediaOne the exif data show as having been changed to 72 dpi only on the rotated picture! But that does not necessarily mean that an up-to-date Adobe product should be using the exif resolution field over the printer resolution field in the first place!

Edit followup: I'm not very good at reading encoded jpgs in Notepad, but it looks like I will be very careful with any originals I rotate in PhotoImpact. PI X3 wiped out not only the exiif data, but also other XMP [IPTC] metadata that I had previously added to the above rotated jpg.
JM_2

[Bobm03]

Sorry for jumping into this thread so late.

I just took a camera jpg from a Canon A-75 point and shoot, with exif resolution of 180ppi and rotated it in PI X3. Then Saved As with a different name.

Please explain exif resolution. I have never heard of this expression and cannot find it in my exif data, anywhere. To me, it's meaningless and says nothing. I am interested only in the dimensions in pixels.

When opened in Irfanview 4.10, both images still show a printer resolution of 180x180 ppi, but the rotated jpg shows exif resolution of 72 ppi, not the original 180ppi. It would seem that, indeed, PI X3 is changing the exif field to 72 dpi on rotated jpgs.

Now, tell me, after you've read Heinz' discussion points again, are you looking at the image on a piece of paper, i.e., printed, or are you looking at the image on the screen? Check, once again, the size of the image in pixels of both images. It remains the same. This is all that matters. Check the Print size of each different "ppi" resolution. Note how the image with the larger resolution is so much smaller.

PhotoImpact's display of camera maker's exif data is incomplete, so the change is not obvious. Now to look in Corel MediaOne. Yes, in MediaOne the exif data show as having been changed to 72 dpi only on the rotated picture! But that does not necessarily mean that an up-to-date Adobe product should be using the exif resolution field over the printer resolution field in the first place!
JM_2

Exactly what more would you like to see in the camera maker's exif information? EXIF data is standardized (currently 2.2) for both camera maker and photo software.

Read and digest what Heinz has said so eloquently.
He is right...this time

[John Moran_2]

Sorry for jumping into this thread so late.
. . . . Read and digest what Heinz has said so eloquently.
He is right...this time

I am not an avid fan of any particular software. I bought PI 6 years ago because it seemed to be the most powerful Photo Editing software for under $100 at the time. I recently bought PI X3 because of price AND fewer reports of installation problems with this version as opposed to PI 11 and PI 12.

That said, I was editing my above post as Bobm03 was commenting on it. It does seem that PI X3 pretty much removes existing metadata - even Keywords - in the process of doing a 180 degree rotation. It does not rewrite that data to the files.

PI X3 is light years behind in displaying camera makers exif data within the program. PI X3 does not yet have a utility for embedding keywords, as it had an externally maintained Album database with earlier versions, and only recently threw in the towel on getting anyone to use it. Ulead PI is not alone in having to give up on fighting the losing battle of crude external file management, including keyword searches.

CorelMediaOne does embed certain metadata fields with the now deprecated "old" Adobe/IPTC headers. It also does a credible job of displaying exif data fields.

On the release date of Vista, in January 2007, Microsoft simultaneously released a very handy metadata properties tool which could embed the newer IPTC core XMP fields proferred and trumpeted by Adobe. Ironicallly, at the same time Adobe was trying to give away a less than satisfactory starter externally maintained Album utility, which it bundled with Adobe
Acrobat Reader upgrades.

And so it goes. I did buy a used printer the other day, and ordered some aftermarket ink to try to get it unclogged and running. If I was smart enough to understand all this stuff I never would have bought it.
JM_2

[Frank]

Can you give me a step by step description of what you did to rotate the page in PI?

I right clicked on the jpg and clicked 'Edit with PhotoImpact' that appears in the drop down menu. PhotoImpact then opens with the jpg in an 'inset' window in the editing field. I then clicked on 'Edit' in the top tool bar, moved the mouse pointer down to 'Rotate and Flip', at which time another menu opened to which I selected 'Rotate 180'. After the jpg rotated, I clicked the red x (close) in the top corner of the 'inset' window containing the jpg. A pop-up window appears saying 'Save changes to (jpg)' with 3 buttons - Yes, No, Cancel. I click 'Yes' and the window closes .... That's it ....

After doing a little research on how Nuance and Acrobat create pdf files, which I found stands for Portable Document Format, it turns out that the programs use document size to make their calculations and not pixel dimension. When jpg¡¦s are scanned at 600 dpi, the Pixel Dimensions are 5100w x 7019h with a Document Size of 8.5in x 11.7in. After rotating and resaving with PI 12, the Pixel Dimensions remain the same (5100x7019), but since the dpi gets changed to 72 the Document Size changes to 70in x 98in. When using the edited jpg¡¦s in conjunction with the non-edited ones, the pdf program sees the two different Document Sizes and compensates. Thus the two different sizes in the completed pdf document. ¡K ¡K. Again, I appreciate all the help , I just didn¡¦t think it would cause this much trouble ¡K..

[John Moran_2]

Frank-
Thanks for your posts and for putting th pictures back on this thread. It was only after I saw that you were using pdf that I understood what was happening. (I did think that PDF was an acronym for Page Description Format in former days.)

I now think it is most likely that Corel Ulead PhotoImpact just strips all the exif data off, including the nominal printer ppi resolution. Then Adobe PhotoShop 7, with perhaps Acrobat, and Irfanview, and Corel MediaOne following suit, default to 72 dpi for resolution display and printing purposes.

I was surprised to find that Adobe, in a link found in a Google search last night, has a white paper that explained how CS could work with 300,000x300,000 pixels, seemingly within 2GB, (or maybe 4GB if a Tiff) and then mentioned Win98 and WinME on the same page.
JM_2

[heinz-oz]

Can you give me a step by step description of what you did to rotate the page in PI?

I right clicked on the jpg and clicked 'Edit with PhotoImpact' that appears in the drop down menu. PhotoImpact then opens with the jpg in an 'inset' window in the editing field. I then clicked on 'Edit' in the top tool bar, moved the mouse pointer down to 'Rotate and Flip', at which time another menu opened to which I selected 'Rotate 180'. After the jpg rotated, I clicked the red x (close) in the top corner of the 'inset' window containing the jpg. A pop-up window appears saying 'Save changes to (jpg)' with 3 buttons - Yes, No, Cancel. I click 'Yes' and the window closes .... That's it ....

After doing a little research on how Nuance and Acrobat create pdf files, which I found stands for Portable Document Format, it turns out that the programs use document size to make their calculations and not pixel dimension. When jpg¡¦s are scanned at 600 dpi, the Pixel Dimensions are 5100w x 7019h with a Document Size of 8.5in x 11.7in. After rotating and resaving with PI 12, the Pixel Dimensions remain the same (5100x7019), but since the dpi gets changed to 72 the Document Size changes to 70in x 98in. When using the edited jpg¡¦s in conjunction with the non-edited ones, the pdf program sees the two different Document Sizes and compensates. Thus the two different sizes in the completed pdf document. ¡K ¡K. Again, I appreciate all the help , I just didn¡¦t think it would cause this much trouble ¡K..

First of all, when I tested this in PI X3, the image resolution did not change after I rotated the image and saved.

That a pdf file is not measured in pixels is nothing new, after all, it is a document. Your image file is not a document, it's an image and measured as such in pixels. Its corresponding document size is governed by the resolution but this setting is usually ignored or replaced by the printer's dpi setting.

I had trouble understanding where you were coming from because I usually print my images and do not create pdf files first.

If you want to include a scanned and edited page into a book with non edited pdf files, you have to make sure that the resolution stored in the image header corresponds to the scanner settings which will ensure that the page in pdf format is the same width as the other pages.

I can't say why your copy of PI resets the resolution header in the image but would advise to check that setting prior to saving the image.