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PostPosted: Fri May 02, 2014 12:22 am 
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I am trying to understand the relation ship between dpi, 16 bit and what will give me the best image quality to work with. I currently post process images using light room and photo shop. I have been saving the files as psd. I noticed as I increase the dpi the image size is reduced? Regardless I would be interested in any advice on providing the "optimal" or "best" image to render. I understand that this will increase the size but diskspace is not an issue. Seems like a basic question but would appreciate some advice.


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PostPosted: Fri May 02, 2014 1:08 am 
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Location: Duesseldorf, Germany
John Pohl wrote:
I am trying to understand the relation ship between dpi, 16 bit and what will give me the best image quality to work with. I currently post process images using light room and photo shop. I have been saving the files as psd. I noticed as I increase the dpi the image size is reduced? Regardless I would be interested in any advice on providing the "optimal" or "best" image to render. I understand that this will increase the size but diskspace is not an issue. Seems like a basic question but would appreciate some advice.



Hi!

dpi or ppi is a term related to printing images only. It means the density of the printed points (dots). As long as you don´t need to print your rendering onto paper: forget about dpi.

Lave it to the default dpi.

The shear AMOUNT of pixels defines the over-all resolution. The size of the plane on which these pixels are placed depends on the sheer amount of the pixels.
Large plane = wider spread pixels = viewing on a longer distance. Small plane = less wider spread pixels = viewing details on a shorter distance. The amount of pixels being the same.

So you can fill a larger plane only if you accept a certain distance between pixels - to be viewed on a larger distance.
So you can fill a smaller plane having lesser distance between the pixels - which means viewing it on shotar distances, which means viewing all the details in the image better: they´re not "pixalised."
Have a very close look to a daily newspaper´s photo: you can see the print-dots. Hold the paper on arm´s length: you mostr likely will NOT recognize that the images is based on many seperate dots.
The standard for offset print in magazin-quality is 300dpi.

Conclusion:
your only concern needs to be: how large does my pano needs to be for being displayed on a screen of a certain size? It´s obvious that a very big screen or the projection via a beamer nees to have more (native) pixels than on a tablet.

Also important these days is: hoi far can i zoom into the pano? Quite obviously a depper zoom needs more pixels for viewing it closer.

See here three examples from my work:

1) 6 fisheye shots of 21mpx each provide 112mpx: http://www.360impressions.de/Wohnung (zoom in)
2) 45 shots with a 35mm lens, 21mpx each provide 700mpx: http://www.360impressions.de/Klap (zoom in)
3) 214 shots using an 85mm lens, 21mpx each provide about 4gpx: http://www.360impressions.de/KBogen413

"16bit" means the color-depth: 4096 steps instead of 256 steps with "8bit" for each RGB color.
during the rendering/editing process ist´s prefrable to use 16bit. After all the editing is finished you can make it 8bit without risk.

But importing 16bit TIFFs into PanoTour Pro also is clever - PTP makes them JPG anyway and can use the 16bit/TIFFs as an optimal basis.

best, Klaus


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PostPosted: Sat May 03, 2014 5:19 am 
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Klaus your the best - thanks for your help. John


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