Paint Shop Pro - changing image resolution

The main upshot from the Point of View of the OP, is not to worry about it.

In realistic terms, the only thing that changes when you play with the DPI settings, is the 'size' of the image. In other words, if you have a picture with a resolution of 1024x768 at 72DPI = a 'size' of 14.2 x 10.7 inches. Same image at 300 DPI = 3.4 x 2.56 inches.

It's the same file, with the same pixel count, so the file size in bytes will be the same, it's just the default 'size' of the image (in arbitary units) that's different.

We're probably talking about inkjet printers here though. My 300ppi files are printed at 2880dpi.

For publication, the same 300ppi files are used, which is very convenient.

Ok. Well still a little confused so, let me put it like this. The image I am currently looking at has a total of 14,501,888 pixels. The print size relating to this picture is 64.9" by 43.1". Now the print resolution is 72 pixels per inch.

However, the actual amount of pixels per inch is 5184. Therefore, am I losing resolution when printing out?

Now, when I change the print resolution to 1 pixel per inch the picture on screen is very pixelated (as you can imagine) if the print size remains the same.

Conversely if I change the print resolution to 240 pixels per inch and the print size remains the same, the amount of pixels changes upwards to 15573 by 10347 which is 161M pixels, thereofre leading to a picture with greater resolution (though now 41mb rather than 10mb)

But still I have an image that doesnt have 14.5m pixels within it.

Getting confused now

Well, after having had a chat with a pal of mine, he recommends viewing pictures at 240 pixels per inch. This has the effect of giving an image with a lot more pixels in it (it also increases the memory usage). He then manipulates the image at this resolution (sharpens it, etc) and when he is happy with the final result, he saves it as a jpeg to minimise memory usage. Now the reason he uses 240 to 300 ppi is because its the sort of resolution required for print outs.

Then when it comes to printing out on my machine, he says just use the printer settings you ant. My printer does 600dpi

right, cracked it. I may well be talking to myself here, but hey-ho, its rather cathartic.

I stick my image in PSP. It shows it has 14million pixels. I go to resize and it shows 72 pixels per inch which actually is 5184 pixels per square inch . Big deal. If i were to print out my image would still be at a resolution of 14m pixels. If a buyer for my print wants the print to be of a greater resultion then I change the resolution to 240 ppi (or 57600 pixels per square inch, then fine. The image quality I assume must be greater (pixel interpolation?) but also the image file size shoots up, and it ends up being an image of squillions of pixels.

It has nothing to do with the quality of the physically printed end product. That depends on the qulity of the printer.

Marvellous

Forget the 14 million pixels, concentrate on 4000 x 3000 or whatever else the image size is.

If you use a ppi of 72 that will be a huge image, if you use 300ppi it will be smaller, but the number of pixels will not change.

When you change the number of pixels to achieve the print size you want, then you are interpolating (making up pixels) to change the pixel count.

The only two ppi figures you need are 72ppi (screen, web, projection) and 300ppi (print, publication) and although you could print at 240ppi there is no need to use this fairly random figure. The 300ppi relates to what the eye can perceive, and doubling that to 600ppi makes for bigger files but no visual difference. Halving to 150ppi gives a degredation that is visible to the eye.