Incorrect PPI Information displayed by PSP

[cjaysnyder]

When opening a file(provided to me) that is verified at 600 PPI, the image information provided by PSP2020 is stating that it is only 72PPI, and the EXIF information provided by PSP2020 states 600 DPI. The file properties in windows from file explorer state the dpi is 600. When I have friends open it up in PS they see it as 600 PPI. It seems that I cant rely upon the PPI information that is provided by PSP. Why is this happening. I don't want to have to manually calculate PPI for every image I need to review.

[LeviFiction]

Where is it saying it's only 72ppi? You say the EXIF provided by PSP states 600 but also say it states 72PPI. Where in the interface does it say this?

[AJ8MH]

I just loaded a test image at 360 ppi. Image info under Current Image Information shows 360 ppi and 360 dpi under EXIF. If I go to resize By Print Size, it’s 360 resolution, which also happens to be my ppi setting under Units in Preferences. This is only applied to images that do not have a resolution value. If I go to Resize by Pixels, Percentage or Based on One Side, I do see a 72, but that’s under Sharpness and that’s not a ppi number...I don’t think.

Now, if I load a jpg from my Canon T6i, all of the above change to 72 ppi, dpi and resolution. That appears to be coming from the camera.

I am using PSP 2018.

[cjaysnyder]

Where is it saying it's only 72ppi? You say the EXIF provided by PSP states 600 but also say it states 72PPI. Where in the interface does it say this?

Within PSP2020 Shortcut to image information "Shift + I"

Screen shots ----> https://drive.google.com/file/d/1eZMmuJ ... sp=sharing

[LeviFiction]

I'm guessing that the EXIF data and the resolution data stored in the format itself are different.

This value isn't an important value anyway, as it'll print at whatever resolution you tell the printer to print at, but if you want to update PSP to use the new resolution you're going to have to force it by using the Resize command. Using the steps below won't actually resize the image, it'll just change the ppi.

1) Open image
2) Image -> Resize
3) click on "by Print Size" along the top
4) Change ppi to 600
5) Click on "by Percentage" along the top
6) change the percentage values to 100
7) Go back to "By Print Size" you'll see the print size has changed but the ppi is still what you had it set to.
Click OK

The image resolution will now match the EXIF resolution.

[hartpaul]

Cameras seem to default to a value of 72 ppi (pixels per inch) which is basically an instruction to the printer telling it to print 72 pixels for each inch of print space , whether that printer be set to 150 dpi (dots per inch) - a draft setting or 600 dpi (600 dots per inch ) - a high quality setting.

This means that when you print that 72 ppi image
150 dpi - each pixel gets about 2 printer dots (150 /72) to represent each pixel - image will look coarse
600 dpi - each pixel gets about 8 printer dots (600 / 72) to represent each pixel - the image will look finer in detail

When you create a new document with the settings you use in PSP via File > Preferences > General Program Preferences > Units - Default Resolution - 600 pixels / inch, then that document will show a resolution of 600 pixels per inch.

I agree with LeviFiction re steps 1-4 but then
5. Tick 'Advanced Settings' and Untick 'Resample using' and click OK. This changes only the ppi value in the image without resampling to make it bigger or smaller.
If you later want to resize images larger or smaller , then you need to retick 'Resample using'

6. Click the i (info) icon on the Standard toolbar it will then show the image ppi as 600

[cjaysnyder]

My question is "Why won't PaintShop Pro provide the actual PPI of the file."
Why when a friend opens up the file in PhotoShop it reports it correctly. PSP should extract the file information no differently than Photoshop.
When I download a file, I want to quickly look at the information to determine if the file is at or above 300 PPI, So I can quickly accept or decline it. The images submitted are scanned images, not images taken by a camera.
I know the difference between PPI and DPI and the PPI is an important value for me as the images are for restoration purposes.
I could sit and manually calculate the PPI but that would take too long when going through hundreds of images.

[Andy2011]

It is possible that the images being referred to have multiple values of 'resolution' and PSP is looking at just one of them.
Photoshop puts lots of addtional information into the metadata (EXIF) of an image it has touched in the form of XMP (XML-like structure). An Adobe application may well read these but since they are non-standard, other applications may not.
Perhaps I am wrong but my understanding is that the resolution is an output measure, not a measure of the quantity or quality of information stored in the image. For example, I can construct and image of 20 x 30 pixels with a resolution of 300 PPI and it will be minute, maybe OK for an icon. I can also construct one of 2000 x 3000 pixels at 72 ppi and it will be vast at full size on a monitor (say 96 dots to inch) but perfectly acceptable as a 4 x6 inch print.

[hartpaul]

My question is "Why won't PaintShop Pro provide the actual PPI of the file."
...
When I download a file, I want to quickly look at the information to determine if the file is at or above 300 PPI, So I can quickly accept or decline it. The images submitted are scanned images, not images taken by a camera.
...
I know the difference between PPI and DPI and the PPI is an important value for me as the images are for restoration purposes.

Your concern over ppi is irrelevant.
You missed out this important part in your first post "The images submitted are scanned images, not images taken by a camera."
Now why is ppi irrelevant for the quality of the image?
You state "When I download a file, I want to quickly look at the information to determine if the file is at or above 300 PPI, So I can quickly accept or decline it."
I presume that you are thinking that the image is low quality if below 300 ppi and high quality if above 300 ppi. This is false thinking.
The ppi value is an instruction to the printer telling it how many pixels to print per inch.

Explanations have been given above about how to change the image resolution without changing the image.
Now an experiment you can do for yourself
1. Take any image with some fine detail in it and crop a 1000 x 1000 pixel section and save that as a jpg preferably in a new desktop folder. Get rid of anything on your workspace and reload that cropped image .
2. You have an image 1000 x 1000 pixels . Check its resolution under image information (the I icon) under Image Information tab. Lets suppose it reads 300 ppi.
3. Make 2 duplicate copies of the image
4. Now use the method in the above posts to change one of the images resolution to say 10 ppi.
Does the image look degraded ?
5. Using the same method change the other images resolution to 1000 ppi.
Does the image look much better?
Compare them side by side. You should see that they have the same pixel dimensions but one has a resolution of 10 ppi and the other a resolution of 1000 ppi .
I repeat the ppi setting is only an instruction to the printer (takes up 4 bytes in the image exif information) and does not change any of the actual image information. So it cannot change the quality of the image on screen.
However as an instruction to the printer it tells that printer how many pixels to squeeze into an inch of print. The more pixels you squeeze into that inch and the higher the printer's dpi setting, the higher the quality of the print.
To get the highest quality of image / print you need sufficient pixels.
A 1 Mp camera / scan has less pixels than a 22 Mp camera. So the 1 Mp camera (1280 x 969 pixels) might have 2 pixels to represent the a blade of grass ## while the 22 Mp camera (5760 x 3840 pixels) has 4.5 pixels to represent the same blade of grass ####/. A little bit more detail.
So when you judge images look at the pixel dimensions and if printing them out change the resolution to what you require - 300 ppi is supposed to be about photo quality.

[JoeB]

@hartpaul's explanation regarding image resolution, ppi and dpi is very good. So @cjsnyder should only be concerned about PPI if print output - and the desired size at a good quality such as 300PPI of such print - is an important consideration.

However, it still doesn't answer the question of why PSP is reading a different PPI using the Image Information tool compared to the EXIF data's reading as well as that of other image editors. @Andy2011 has provided what might be an explanation but it wasn't presented in a manner that indicates that it is definitive. Like @cjsnyder, I am curious to see if anyone has a definitive answer.

[LeviFiction]

No idea JoeB. I doubt we'll have any definitive answers unless Corel dains to descend and offer a possibly explanation. I also mentioned, and truly believe, it's a difference between EXIF and Non-EXIF metadata.

JPEG files have 3 different standard formats that they can be written in, with a lot of additional application specific extensions which makes them very annoying. There is JFI, JFIF, and Exif formats. The Exif format, often used by cameras and scanners but not always, uses TIFF 6.0 data tag format for storing meta data. JFIF uses the APP0 tag to store the resolution of the image, and might also include a TIFF EXIF information segment. And I couldn't find good documentation on how JFI works.

Also, without seeing an example image and learning how to manually parse the file formats (the instructions I found are either above my abilities, or badly written, couldn't duplicate them manually using a HEX editor) there's no way for me to tell if there are two competing resolution information tags inside the file that PSP is reading. The fact that it shows EXIF specific resolution and normal resolution does suggest multiple tags though. Possibly JFIF format. Actually if you open the image in a hex editor (I like HxD myself) you should see either Exif or JFIF written out near the top of the file. I suppose Notepad will also work but if it's a large file a hex editor is almost always more efficient.

I did try to recreate the problem. I opened an image in Photoshop, changed the resolution using the exact same resize trick that PSP uses. I saved the image and opened it in PSP, both the non-EXIF and EXIF meta data matched. So i wasn't able to create an example to test with.

[hartpaul]

Well I managed to duplicate the results that the OP complained about. I used a scanned image at 300 PPI and loaded it into PSP and Image information showed it as 300 PPI under both Image Information and Exif information.
I used an old Hex editor called XVI32 to read in the info from a normal jpg with resolution 72 PPI

The highlighted bytes 00 48 00 48 represent the Hex values for 72 and are repeated for the X value and Y value. 48 = (4 x 16 ) + (8) = 64 + 8 = 72.
These are the only values changed when you change the resolution of an image so the data remains untouched.
Now what I did was to change that second value to 02 58 = (2 x 256) + (5 x 16) +8 = 600
You can check using a Decimal to Hex converter
https://www.rapidtables.com/convert/num ... o-hex.html

This when read into the Hex editor showed

The green is 72 PPI and the red is 600 PPI

When the image was checked in Irfanview it showed this

03Irfanview72 x600.jpg (63.91 KiB) Viewed 1943 times

and the Exif information in Irfanview showed this

Now when that image was in PSP 2020 then Image Information showed 72 PPI and Exif information showed 600 PPI exactly as the OP pointed out.

Now the pixel information remained the same so the quality of the image was unchanged.

I then used the Resize operation to change the resolution to 300 PPI. Again the pixel dimensions and quality stayed the same. This time however both Image Information and EXIF tab in PSP showed 300.
Under the HEX editor the values were 01 2C 01 2C = 300 PPI.

[cjaysnyder]

...Your concern over PPI is irrelevant...

I presume that you are thinking that the image is low quality if below 300 PPI and high quality if above 300 PPI. This is false thinking.

...Now why is PPI irrelevant for the quality of the image?

Paul Thank you for reviewing and trying to help provide a reason why this product will not provide the correct information from the exact same file that PhotoShop has no problem reporting.
Though some of your assumptions about my requirements are incorrect.

The concern over PPI is relevant, not that it has anything to do with MY perception of the quality of any image. I am nothing but a cog in a wheel, following the directions/standards that have been
put in place for files that are submitted by individuals that are directed to make sure that the images they provide must be at least 300PPI. This value is not specified by me, but by the Great Machine
of which I am only a cog found within. So the PPI is relevant, as the Great Machine will never be able to effectively communicate to a group of boomers, that had problems programming their VHS to record,
how to determine if the image they submit is suitable for restoration.

Thank you for taking the time out to recreate the problem. The information you provided was interesting. Nice to see someone that uses a hex editor.

[LeviFiction]

Really quick, Hartpaul proved that PSP is showing the correct information. The "error" is in the file. In Photoshop I can only see EXIF data not the base meta-data. So as long as you look in EXIF the data will be exactly what you see in Photoshop.

It would be very easy to create a simple script that looks at the EXIF data and presents you with a small message box that says "approved: <PPI Value>" or "Rejected: <PPI Value>" whenever you ran it. It wouldn't be much faster than going to the Image Information dialog, and selecting EXIF but it would work.

[hartpaul]

cjaysnyder I can understand your problem now. It is not you, but the ignorant rulemakers who laid down the rules.

I have experienced similar at a local Camera Club where in the monthly competitions for projected images the instructions are :

Images must be 2MB @ 300ppi (or 72), sRGB, JPEG, 1920px x 1080px (max)

It used to be only 300 ppi but recently they accept 300 or 72 ppi, but again whatever figure is used is insignificant.

That can be simplified and made so much easier for members by changing the rule to :

Images must be sRGB, JPEG, 1920px x 1080px (max)

There is still this underlying suspicion that anything less than 300 ppi involves a reduction in quality of the projected image, whereas the truth is that it is only applicable if the image is printed.

You point out that the ppi = >300 reason is to decide if the image is suitable for restoration yet I suggest that you can have an image that is 10 x 10 pixels AND 300 ppi and according to the qualification that image should be suitable for restoration.

How about an image that is 100 x 100 pixels AND => 300 ppi , that should also be suitable for restoration .

But an image that is 5000 x 5000 pixels AND only 10 ppi or 72 ppi would be definitely inferior and unsuitable for restoration, Crazy , what!!!???