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Robes Silver Member Nikonian since 07th Oct 2008
Thu 08-Nov-12 04:57 PM | edited Thu 08-Nov-12 06:27 PM by Robes

I'm having a difficult time understanding the resolution situation. I understand how in Photoshop(PS) you can take an iPhone5 72ppi (3264x2448) image and it does not need to be upsampled to print at 306ppi (2448x3264pix) giving a 8x10 print using all the pixels and if printing at a wanted ~300ppi. If I wanted to print this image at 24x32 it would print at 102ppi indicating I may wish to upsample, add more pixels.

If I save the iPhone pic at 306ppi & 8x10" file size (no upsampling) it uses all the pixels supplied. If I open this pic to view it, it looks identical to the original, being fuzzy with loss of detail.


If I take a pic from a real camera the info from PS gives:

300ppi 13.3x10"(W/Ht) 4000x3000pix 2.6MB

A photo from iPhone5 info from PS gives:

72ppi 45.3x34'(W/Ht) 3264x2448pix 3.49MB

** I can take this iPhone pic & upsample in PS to give the following info:

300ppi 13.3x10" 3990x2993 (essentially 4000x3000) 4.45MB

So at this point,except for file size (2.6MB vs 4.45MB) both pics (one from a home camera & one from iPhone5) are sized the same. If I open each on my iMac the home camera pic is far superior in detail, sharp & crisp to the iPhone pic, even though the iPhone pic has almost double the total MP. The iPhone pic always looks the same on the monitor compared to its untouched original. How can the iPhone image have so much more total MB comparable number of pixels& size yet look so much inferior? What am I missing here? Why does the home camera pics look so much better even when I supposedly make both (home camera & iPhone) pics of equal quality?

The home pocket camera takes pics at 300ppi resolution. The iPhone takes at 72ppi resolution. Import both pics to my computer (27" iMac 2.8 GHz Quad Core i7; 8 GB DDR3 SDRAM 2x4; 2 TB Serial ATA Drive; ATI Radeon HD 4850 Graphics with 512 MB) and they are not the same quality when viewed on monitor. My monitor is set to 2560x1440 resolution and the monitor views both pics at 108.79ppi. When the iPhone pic is processed to match the camera pic via PS (changed from 72 to 300ppi & equal size) it still looks significantly of lower quality. I don't understand how this can be when the iPhone pic has the pixels to work with. How can the two similar resolution/sized pics look so much different in quality?

The iPhone5 display is 1136x640 with 325.97ppi. So, the 3264x2448 72ppi pic it takes looks excellent on it's display. I cannot make this pic look good once downloaded to my iMac but why not? Why does the 300ppi camera pic look so good on my iMac display when compared to iPhone pic yet both are displayed at my monitors 108.79ppi?

I've read that the ppi of the camera makes no difference on a computer screen, if so, what makes one image so much better looking then the other?

Thanks Everyone-

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