Unable to Save .PNG Files at 300dpi in X4

[mesmith322]

I have a .pspimage file that the information shows the resolution as 300dpi. When I try to save it as a .png file, the resolution changes to 118dpi. It doesn't matter if I just do a Save As or File > Save for Office > Professional Printing with 300dpi, the outcome is the same.

[LeviFiction]

Actually, mesmith, if it's doing the same thing to you that it is doing to me then it's showing it at 118 dpc or ppc. If you look closely does it say it's Pixels Per Inch or Pixels Per Centimeter? If you convert 118 Pixels Per Centimeter to Inches it comes out to be 300dpi or ppi.

[mesmith322]

Actually, mesmith, if it's doing the same thing to you that it is doing to me then it's showing it at 118 dpc or ppc. If you look closely does it say it's Pixels Per Inch or Pixels Per Centimeter? If you convert 118 Pixels Per Centimeter to Inches it comes out to be 300dpi or ppi.

OMG, you're right! Do you know why it shows inches with the .pspimage file and centimeters with the .png file?

[Ken Berry]

Is it possible that the inch measurement is embedded with the image from a previous version of PSP (or another program) set up to use dots per inch. But the new default measurement is pixels per centimetre? At least on my X4, the latter is the default under Preferences > General > Units -- though of course you can change it.

[mesmith322]

Is it possible that the inch measurement is embedded with the image from a previous version of PSP (or another program) set up to use dots per inch. But the new default measurement is pixels per centimetre? At least on my X4, the latter is the default under Preferences > General > Units -- though of course you can change it.

Actually, I have the default resolution under general preferences set to 300 pixels per inch.

I looked at a bunch of different files and found that while .pspimage and .jpg files are showing as pixels per inch, EVERY .png file I looked at from multiple sources are showing pixels per centimeter. So, either pixels per centimeter is inherent in .png files (which doesn't make sense) OR it's a bug in Corel X4. I haven't run into this before so I tend to think it wasn't this way in X3. I uninstalled X3 so I can't check it.

[Ken Berry]

Hmmm... yes, I see what you mean. I have the same thing with my png files opening in ppc, but no others (well, at least the pspimage, jpg, gif and tiff files I have available right now). I too have resolution set to pixels per inch. Even resaving one of the existing png files with another name still results in the new one being ppc and not ppi.

[mesmith322]

Ok, it's definitely a Corel or PSP thing. I just opened my .png file in Snag-It and it showed 300dpi.

[eL_PuSHeR]

I remember to have seen this behaviour under X3 too. I usually pay no attention to it because as you have already said 118ppc = 300 dpi.
I also have the default resolution setting at 300dpi (even if we work with centimetres instead of pixels here). I think it's something called International measure system versus Imperial System, or something like that. Hell, it's time the world should unite measure systems.

And yes, now that we are talking about it, it seems to affect PNGs only. Can anyone else confirm?

[mesmith322]

I remember to have seen this behaviour under X3 too. I usually pay no attention to it because as you have already said 118ppc = 300 dpi.
I also have the default resolution setting at 300dpi (even if we work with centimetres instead of pixels here). I think it's something called International measure system versus Imperial System, or something like that. Hell, it's time the world should unite measure systems.

And yes, now that we are talking about it, it seems to affect PNGs only. Can anyone else confirm?

It's only doing it on .png files.

[eL_PuSHeR]

According to PNG's article on Wikipedia, I am unable to locate where PNG files store the resolution value. It should be in the HEADER. It only contains width and height values.

[LindaSue]

The only other graphics program that I have on my computer is IrfanView and it shows both dpi and pixels per centimeter for PNG files. I checked the image info in PSP5, PSP7 and PSP8 and they all show pixels per centimeter for PNG files. PSPX2 shows pixels per millimeter rather than centimeter.

[LeviFiction]

From what I understand PNGs naturally save the value in meters it's up to the program reading it to do the conversion. Of course that's only what I understand, reality could be a whole lot different.

[eL_PuSHeR]

LeviFiction:

You are probably right. I am not sure either.

Linda:

I also have Irfanview. As far as I recall it always displays resolution as pixels per inch (at least for a few PNGs I have tried). Could you post some sample image to test?. A tiny one would suffice.

[LindaSue]

LeviFiction:
Linda:

I also have Irfanview. As far as I recall it always displays resolution as pixels per inch (at least for a few PNGs I have tried). Could you post some sample image to test?. A tiny one would suffice.

You're right. I was looking at the Print Size rather than the Resolution in the image properties. I also see pixels per inch in IrfanView. The question is why does PSP only show centimeters???

Here's another puzzle. I just randomly opened a PNG file that I'd downloaded from somewhere and it shows in PSP in DPI instead of centimeters. I resaved it with PSP and now it shows centimeters in the image properties. Up until that one file, every PNG file that I've viewed in PSP showed centimeters so I assumed that PSP was viewing them all that way. Apparently that's not the case. The odd thing is that I can't seem to find any other PNG files that show DPI except that one. I'm sure that all of the PNG files that I've found online can't have been saved with PSP. Most scrapbookers seem to use either Photoshop or PS Elements, not PSP. I've got hundreds of downloaded transparent PNG files so I can't possibly check all of them but I haven't found any others that show DPI by just randomly opening a few. Now I'm wondering what is different about that one file that it's showing DPI in PSP. I can post the fie here if anyone wants to check it out.

[eL_PuSHeR]

LindaSue:

This is a puzzling issue indeed. I am at my wits end here. I don't know what makes PSP get dpc in file info instead of dpi. Unfortunately I can only test using X3, because, right now, X4 is unuseable for me (hopefully waiting for a patch/service pack). But as I have said before X3 also exhibits this same behaviour.

I am going to try saving a PNG file with several different viewers later to see what X3 shows under info.

This is what I found out:

Saved a small paletted png image as anything else with the following programs:

+ MS Paint (W7)
+ Irfanview
+ XnView

All of them showed resolution as pixels per centimeter when loaded under X3. I checked X3 preferences -> General -> units and everything was set for working with PIXELS. Default resolution was set to PIXELS PER INCH. Changed everything to centimeters / ppc but it was the same. No change at all.