XResolution and YResolution

[Monin]

I have a Nikon 4800. In the EXIF Tags it says:

XResolution: 300
YResolution: 300

My Brother owns a Panasonic Lumix DMC-FZ30; in the EXIF Tags it displays:

XResolution: 72
YResolution: 72

Does it means my Nikon 4800 takes better photos? Is that a measure of quality of the photo?

Thanks in advance for any help in this matter since I am thinking to buy a new camera and want to know if XResolution and YResolution is something I should look for.

[cwphoto]

I think this just some sort of nominal resolution and doesn't affect the 'real' resolution of the camera - but someone else here can explain why I'm sure.

[kgosden]

You are correct. A digital photo has no real dpi, nor does any digital image, until printed. When you actually print or display an image then the pixels are rendered in physical space where dpi has meaning. Even there your photo is still only as detailed as the actual pixel count regardless of your print being 3x5 inches or 3x5 feet. All that matters to resolution in the digital world is the actual pixel count.

Think about it in terms of your actual image. If you take a photo of someone from 40 feet away maybe their face is only 12 pixels high, move in closer to fill the frame and now it is 1200 pixels high. Did the 'resolution' of the total picture change? But if their face is 12 inches tall then one photo is 100 dpi and the other is 1 dpi; at least relative to the actual content. However, even that is not a valid concept. What about that speck of a skyscraper sticking up over the top of the person's head in the first image; it might be 100 feet tall and only 12 pixels high in the image.

[Monin]

You are correct. A digital photo has no real dpi, nor does any digital image, until printed. When you actually print or display an image then the pixels are rendered in physical space where dpi has meaning. Even there your photo is still only as detailed as the actual pixel count regardless of your print being 3x5 inches or 3x5 feet. All that matters to resolution in the digital world is the actual pixel count.

Think about it in terms of your actual image. If you take a photo of someone from 40 feet away maybe their face is only 12 pixels high, move in closer to fill the frame and now it is 1200 pixels high. Did the 'resolution' of the total picture change? But if their face is 12 inches tall then one photo is 100 dpi and the other is 1 dpi; at least relative to the actual content. However, even that is not a valid concept. What about that speck of a skyscraper sticking up over the top of the person's head in the first image; it might be 100 feet tall and only 12 pixels high in the image.


Thanks for your detailed explanation.

What do you mean by "actual pixel count"? Is it "Width x Height" which will be:
2288 x 1712 = 3.917.056 pixels for the Nikon Coolpix 4800
3264 x 2448 = 7.990.272 pixels for the Panasonic

That total number of pixels are the ones that actually matters?

[kgosden]

Yes, the actual pixels in the original image.