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 81 
 on: October 17, 2017, 09:31:02 AM 
Started by petercorb - Last post by Miles
No, I am from the USA but took the opportunity to visit South Africa for two weeks with my daughter a few years ago.  Cape Town was one of the areas we chose to visit along with Kruger National Park and other special areas.  Viewing the South African penguin and their vocalization was quite quite a treat for both of us along with the vast array of animals in/near Kruger.  South Africa is truly a beautiful, diverse land and is well presented on your website.

Miles

 82 
 on: October 17, 2017, 09:20:52 AM 
Started by Chris Sanderson - Last post by GrahamBy
Claire

 83 
 on: October 17, 2017, 09:13:32 AM 
Started by aaronchan - Last post by BartvanderWolf
Very useful Bart. So here in Canada where we can be both metrically and "imperially" challenged, and as I grew up in the "imperial system", let's use feet; assuming my viewing distance of a 13*19 sheet is arm's length, or about two feet (depending on your arms), and my vision is well-corrected, I can divide the 716 by 2 and I'm close to  360, which is one of the native resolutions (perhaps the most often applicable) of the Epson print head.

Yes, that's what the output file's PPI should be to meet the required visual acuity when viewed from that distance. Viewing it from a larger distance will not resolve more if the eye cannot resolve finer detail, the details will just become smaller to the eye and the finest detail can no longer be resolved. The contrast by which the eye resolves detail will become too low to separate details as one approaches the limiting resolution of one's eyes. That contrast varies with detail size. This also allows to visually improve resolution by boosting the contrast of the finest detail, with output sharpening.

Quote
But I could print lower and still be well within range of average human visual acuity - in fact according to this data at 140 PPI. This range makes sense to me, as I've seen from my own testing that from about 180 downward one begins to see the appearance of sharpness deteriorating, and below 140 is "no go" territory.

That's how that works. Of course, we photographers are not normal people so we tend to look at image detail from very short distances. So to somewhat satisfy that requirement, one could use a normal reading distance of 1 foot (or instead, the length of one's nose if a forensic analysis is required) for minimum required PPI. One can also put an obstacle, like a couch or table in front of the wall ...

This also assumes viewing at reasonable illumination levels, because at dark conditions our eyes lose resolution to spherical aberrations, and at high illumination levels we'll get into diffraction limited eye resolution.

Cheers,
Bart

 84 
 on: October 17, 2017, 09:12:40 AM 
Started by Francesco Carucci - Last post by HSakols
I like the high key light.  It certainly was a beautiful weekend! 

 85 
 on: October 17, 2017, 09:04:01 AM 
Started by Dinarius - Last post by Dinarius
Sorted:

In Photoshop's File/Scripts/Image Processor, you simply have to put in 2048 (or whatever size you want the long side of the image to be) in BOTH boxes.

Photoshop then makes the long side 2048, while scaling the short side to retain the aspect ratio.

It does this whether the image is portrait or landscape format.

Brilliant!

D.

 86 
 on: October 17, 2017, 08:52:19 AM 
Started by rasworth - Last post by Mark D Segal
That's a question that can be resolved simply by analyzing the profiles with M2 and M3. Or colorimetric prints made with them viewed side by side. By definition, if the prints are illuminated in the same manner as profiles are made, that is from the side at 45 degrees, the reflectance of D50 from the prints will match the M2 profile uV effects aside. If the M3 profile differs then the illuminated print will not be the same using colorimetric intents (Perceptual and BPC realigns the tone curves but not the saturation reduction). How visible the difference is depends on the magnitude of the difference and the simplest approach is to compare the profiles.

In my experience comparing numbers and 2D/3D diagrams of many profiles with their corresponding prints, I've come to the realization that numbers and diagrams only take you so far, then you need to look at the prints. The numbers and diagrams are useful so I use them, but prints are the final product - the rest is inputs. The print producer needs to care about the inputs, but not be mesmerized by them. My normal viewing environment is roughly in the range of D50/45degree to the light source, but not exactly, so my comparative vantage point is within a range of near consistency, and I've seen disconnects between what one may infer from data and what one sees on paper - sometimes rather glaring ones - so one needs to have a balanced approach to reliance on inputs and product in deciding what works best for the print of a photograph (not a patch chart).

 87 
 on: October 17, 2017, 08:31:15 AM 
Started by aaronchan - Last post by Mark D Segal
Very useful Bart. So here in Canada where we can be both metrically and "imperially" challenged, and as I grew up in the "imperial system", let's use feet; assuming my viewing distance of a 13*19 sheet is arm's length, or about two feet (depending on your arms), and my vision is well-corrected, I can divide the 716 by 2 and I'm close to  360, which is one of the native resolutions (perhaps the most often applicable) of the Epson print head. But I could print lower and still be well within range of average human visual acuity - in fact according to this data at 140 PPI. This range makes sense to me, as I've seen from my own testing that from about 180 downward one begins to see the appearance of sharpness deteriorating, and below 140 is "no go" territory.

 88 
 on: October 17, 2017, 08:27:04 AM 
Started by Dinarius - Last post by Dinarius
I want to batch resize a folder of Jpegs (of differing sizes) to all be 2048 on the long-side, and let the short side resize proportionately. i.e. I want them all to retain their own aspect ratios, while being 2048 on the long side.

Is this possible to do?

Thanks.

D.

 89 
 on: October 17, 2017, 08:09:02 AM 
Started by Harald L - Last post by Bob_B
Yes, really nice set, especially third one (op).

 90 
 on: October 17, 2017, 08:01:36 AM 
Started by rasworth - Last post by Alan Goldhammer
I do not print on canvas but from my reading on LuLa, most printers coat canvas prints prior to framing.  Does the use of such coatings mean that the profile which is likely done on non-coated canvas targets is not as accurate?

Doug Gray is correct about viewing conditions.  I was down at my old office over the summer taking some light measurements of a series of prints that have been on display for 10 years.  I wanted to get some Lux measurements to get an idea about print stability.  I should have hung a color checker swatch that could be measured for fading but folks would probably have thought it was just some kind of op-art print.  As I reported at the time, the prints still look as good as when they were originally hung.  It's interesting that the display conditions, traditional office lighting, are illuminated at almost the 45 degree angle that Doug mentions. 

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