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11-29-2018, 11:45 AM - 1 Like   #46
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QuoteOriginally posted by BrianR Quote
His photographic skills were also put into question, so his galleries are also worth a link:

Clarkvision.com Index of Photo Galleries
If you are saying what I think you are saying then I agree with you in as much as he appears more than adept with his imaging. I like many of his landscape film and digital and would be happy to hang some on my wall. I found his Astro work stunning even though I am not into that freely admit clueless about even the first steps


Last edited by TonyW; 11-29-2018 at 11:51 AM.
11-29-2018, 12:15 PM   #47
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QuoteOriginally posted by BrianR Quote
His photographic skills were also put into question, so his galleries are also worth a link:

Clarkvision.com Index of Photo Galleries
He posted a poor series of images so how does that help? Is his camera really that bad that it produces that kind of quality pixel peeping even though he's a top level photographer? He didn't even explain what those images were in terms of the magnification. For all I know those images were magnified to the size of a 20 foot print, just to make a point.

All I know is he thinks he's on to something. But, being a good photographer in no way means he knows what he's talking about from a technical perspective. You don't have to be an aeronautic engineer to fly a plane. I'm looking for an academic credential suggesting he has a clue what he's talking about. And without double blind testing, I don't even know if he sees what he thinks he sees, or even if he does, if there is another person in the world who sees what he sees.

Last edited by MarkJerling; 11-29-2018 at 02:15 PM. Reason: Keeping it friendly.
11-29-2018, 12:18 PM - 1 Like   #48
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QuoteOriginally posted by normhead Quote
He posted a totally crap series of images so how does that help? Is his camera really that bad that it produces that kind of quality pixel peeping?
Rather than continuing to criticize the fellow on PentaxForums where he won't see it, how about you take it up with him? His contact info is here: ClarkVision.com: about R. N. Clark
11-29-2018, 12:38 PM   #49
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QuoteOriginally posted by BrianR Quote
Rather than continuing to criticize the fellow on PentaxForums where he won't see it, how about you take it up with him? His contact info is here: ClarkVision.com: about R. N. Clark
Why don't you take it up with him? I didn't post this junk here and I'm not defending it. I'm merely pointing out it's weakness as "evidence" of anything.

I've taken a lot of my time to offer a critique of his work. Time for others to contribute some of their time if they want to keep this going.

I made specific points. That's all I'm interested in discussing.
Tell me where I'm wrong.

Tony is actually a printer. If he tells me that with a 600 DPI printer you need two rows of lines to make one line, making it effectively a 300 DPI printer, I'll be happy to go with that. Sometimes stuff just doesn't make sense.


Last edited by normhead; 11-29-2018 at 01:00 PM.
11-29-2018, 02:33 PM   #50
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QuoteOriginally posted by dsmithhfx Quote
Thanks for the link. I did not know you could configure browser color management.
Well for the majority of people it won't really be necessary. If you use an un-configured browser, and a normal (not wide) gamut screen, and you look at pictures that are in the sRGB colour space you wont see any difference.

With a wide gamut monitor things are different.
11-29-2018, 03:06 PM   #51
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QuoteOriginally posted by pschlute Quote
Well for the majority of people it won't really be necessary. If you use an un-configured browser, and a normal (not wide) gamut screen, and you look at pictures that are in the sRGB colour space you wont see any difference.

With a wide gamut monitor things are different.
Respectfully, I'd disagree here...

Regardless of the display's gamut, if your browser isn't colour managed, you won't see images displayed in it accurately. They might look OK, but the colours, whites and blacks won't correctly reproduce what's presented in the image data. Depending on the screen and the default or user-adjusted profile in use, this can vary from relatively mild to horrible inaccuracy. It can be especially bad on laptops, tablets and phones, where the screen and default profile often result in a high contrast, cold, blue-biased rendering.

For anyone viewing or editing photos and wanting realistic colour and tone reproduction, it's well worth creating a suitable calibration profile with a colorimeter and software (I use a Colormunki Display colorimeter and DisplayCAL + ArgyllCMS software), and configuring the operating system, browser and any other colour managed applications to use that custom (or, if the option exists, the operating system's selected) profile.

EDIT: I just took delivery of a new / old stock Lenovo 2-in-1 Windows 10 laptop / tablet yesterday (snagged as a Black Friday deal). After installing the seemingly-endless Windoze updates (which took an entire day ), the very first thing I did was to install ArgyllCMS and DisplayCAL, hook up my Colormunki Display colorimeter, and calibrate the display. Now, everything looks correct on my main laptop, external display and 2-in-1. Not identical, but very, very close...

Last edited by BigMackCam; 11-29-2018 at 03:26 PM.
11-30-2018, 07:34 AM   #52
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QuoteOriginally posted by BigMackCam Quote
Respectfully, I'd disagree here...
Yes sorry, you are right.

11-30-2018, 09:46 AM - 2 Likes   #53
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QuoteOriginally posted by normhead Quote
....Tony is actually a printer. If he tells me that with a 600 DPI printer you need two rows of lines to make one line, making it effectively a 300 DPI printer, I'll be happy to go with that. Sometimes stuff just doesn't make sense.
Thank you normhead. As a printer and photographer (would be for the latter for the last 12 years - personal reasons) {Pedant mode:ON} I cannot actually tell you precisely that {Pedant mode: OFF} , but you are certainly in the right direction. And, yes sometimes it is hard to make sense of stuff and once we think we have made sense then someone throws new or contradictory information into the barrel and off we go again!

Please take the following in the manner it was intended that is informing. I am not here to try to teach or preach, I do not try to tell people what they should see or do and I do not always follow my own advice or suggested best practice . I have learned a lot from this and other fora and generally have taken away more than I have contributed. So my contributions are really trying to help others based on my working experience and if it is just theory or guesswork I will endeveour to make sure I mention this.

Ok, so I am picky and try to make sure we are talking like for like and comparing apples to apples. To make sure of no confusion I try not to use the catch all DPI my first photographic mentor and boss beat this into me! I know that this may be teaching granny to ...

When referring to scanners for instance I use SPI (samples per inch). Inkjet printers have two resolutions one that is declared to the OS which is its requirements measured in PPI and the only thing that our editing programs are interested in.

The second and least appreciated (IMO) is DPI. A printers dpi specification is pretty meaningless in relation to the ejaculation (I have a dislike of the misuse of the word Giclee quite affected again IMHO!) of ink onto paper. The dpi specification is merely the pitch of the stepper motor usually seen as two figures in the specs. I do not think in terms of dots either because the printer 'squirts' ink onto paper and that volume of ink does not have a fixed size it will spread according to variable such as substrate absorption paper surface type and many other factors...It can take many DPI to form 1 PPI

So to finally arrive back at your first statement the only change I would make is that generally there is a hidden agenda within your print driver and although 300/600 PPI and 360/720 PPI quoted as declared to OS the actual max is probably double this. I have two main printers an everyday Canon TS 8000 series and Epson P800 the actual maximum resolution is 1200 PPI for the Canon and 1440 PPI for the Epson. So as you said 1/2 the maximum resolution brings us back to 600 PPI Canon and 720 PPI Epson. I have never seen any IQ improvements printing over 720 PPI my own or others work. However I have until recently limited myself to outputting from either LR or PS. Results may well be different via another specialised printing application either RIP or something I have but rarely use Qimage. Mike Chaney has showed some advantages to IQ for certain images printing at the higher PPI. I am well aware of viewing distance and how it should or may not matter if you are far enough away - still if you do get close you may see what your capture system is capable of.

On the matter of Dr Clark well he came or was brought to my attention many years ago when I was researching digital imaging sharpening and optics.

Dr Roger Clark PH.D Planetary Science MIT 1980
Over 300 scientific papers posted
Team member of certain NASA bodies
Team member on the Cassini mission to Saturn
Lead the USGS environmental assessment of the World trade Centre diasaster
Lead the 2010 Deepwater Horizon Gulf of Mexico oil spill.
Hirsch citation index: H-index= 72 (2017)

I have faith in Dr Clark judgment and assessment as do many others including those that pointed me in his direction many years ago. Does he know what he is talking about photographically, optically visually I would say yes he does. Regardless of this I would and have proven and demonstrated to myself and others some of the points he covers.

Perhaps his choice of image last updated in 2009 could have been better, that is his call and nearly 10 years on he is unlikely to add more? What he published and what I linked to cannot by any means be considered junk. With the benefit of hindsight I could have pointed to another learned article and author – his just came to mind.

The image depicted is a small section from a 5x4 film.

I will try and comment on at least some of the points you made in an earlier post on this thread at least to the best of my knowledge and understanding - there may be controversy . Hope that did not come across as pompous

EDIT: Just to prove I do take photos and print them my table with recent test prints and a restoration work from finished B&W to hand coloured for a project I am working on with a client. Nothing wonderful but the image with rhe rule on top is going to be a 60"x17" print to go in a spare bedroom (to hide the poor plaster repair I made prior to painting). I may post something more on this image - from a photographer that really hates the fact that he cannot hold his iPad or Android phone steady!!

Last edited by TonyW; 04-30-2019 at 12:12 PM.
11-30-2018, 10:32 AM - 3 Likes   #54
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QuoteOriginally posted by BigMackCam Quote
Thanks, Steve...

Given that, what's the point of a 4K 15.6" screen, if any?

Frankly, I didn't select this screen for the resolution, but for the colour gamut. I'd have been just as happy - happier, perhaps - if I could have chosen an FHD resolution screen with the same gamut, but such an option wasn't available on this or any other laptop I considered. So I'm OK with the fact that I might not get any advantage from a higher resolution screen of this physical size. But I'm hoping that I haven't actually reduced the quality of my photo editing experience by choosing it...
At some level, your editing might improve because a 4k 15.6" display with the image set to 100% will actually give you a very good idea of how the image will look printed at 300 ppi. At that resolution some of the pixel-peeping artifacts you would have edited on a low-res display at 100% might be invisible (as they would be invisible on the print) so you won't be tempted to waste time editing them.

But if you are addicted to pixel peeper editing, then you'll need to go to to 200% or 400% to magnify the artifacts.

If you have (or can get) a 4k TV and your new laptop has an HDMI port, then there's a good chance you could mirror or extend the desktop to the TV. The TV would act as a larger monitor that shows you more of the image.
11-30-2018, 10:38 AM - 1 Like   #55
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^^ This ^^
11-30-2018, 11:13 AM - 1 Like   #56
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QuoteOriginally posted by photoptimist Quote
At some level, your editing might improve because a 4k 15.6" display with the image set to 100% will actually give you a very good idea of how the image will look printed at 300 ppi. At that resolution some of the pixel-peeping artifacts you would have edited on a low-res display at 100% might be invisible (as they would be invisible on the print) so you won't be tempted to waste time editing them.

But if you are addicted to pixel peeper editing, then you'll need to go to to 200% or 400% to magnify the artifacts.

If you have (or can get) a 4k TV and your new laptop has an HDMI port, then there's a good chance you could mirror or extend the desktop to the TV. The TV would act as a larger monitor that shows you more of the image.
I tend to make those kinds of decisions based on lw/ph. When I print, I'd like to have 100 distinct lines per inch. So with a K-1 image with a measured resolution of 3500 lw/ph, I can print 35 inches at that resolution. With some landscapes even 70 distinct lines per inch is fine meaning as high as 50 inches.

The issue for me is, there isn't a 1:1 relation ship between pixels and lines per inch, coming from the camera. The K-1 rated at 3500 lw/ph is 5000 pixels deep. One line of pixels doesn't give you one line resolution, coming from the camera. It doesn't matter what size the original image is to me in these kinds of decisions. Only that I get 100 line per inch measured resolution. I'm going to upscale my image to 300 DPI for the printer, so the 300 DPI is a going to happen one way or the other. Because we upscale our images what they will look like at 200 DPI on monitor is irrelevant. What the image looks like on the monitor after upscaling is more the issue.

In practice, our preference is to edit on 110 DPI. 200 DPI looks sharper than it really is in most of our prints., so It's harder to evaluate sharpness, micro contrast etc. But to use a 4k moniotor to judge how your image is going to look like printed at 300 DPI a few things have to happen.

I have to decide what size I'm going to print.
Example, I'm printing 30x20 image.
To get 300 DPI (or more often these days 360) I have to make my 7000 pixel wide K-1 image (or 6000 pixel wide K-3 image) 30x300= 9,000 pixels wide.
After I upscale, looking at 4 k with 300 dpi would give me a pretty good idea how my final image would look.

But just for editing purposes that would really slow down your editing process to have that big a file (54 MP) would make editing inefficient. We always work on images at native size. Resizing is the last thing we do.

So I actually find the 27 inch 110 DPI monitor to be the best compromise. We've never had an image we edited on that monitor disappoint us. We definitely can't tell if the image is good, on a 21 inch 4k monitor. Saying a 4k monitor is akin to what the print will look like is true if (and only if) you've expanded or reduced your original image to the size of the export file before you make that determination. I haven't found that to be necessary. So far calculating the real resolution in lw/ph has worked great. If you have 100 real lines per inch, the print will probably exceed your expectations.

The only way a 4k 220 DPI monitor shows you what the print will look like pixel peeping will be if you print a 7300 x 5000 K-1 image at 300 dpi at 24.25 x16.67 inches, and then adjust to make up for the fact that one is 300 and one is 220 DPI. It's really not a practical suggestion. Every monitor is going to be perfect for one size of image. A 4k monitor is good for one size. my 3k monitor is good for one size, a 2 k monitor would be good for one size. There's no specific advantage to 4k, unless it aligns with the size you are printing that day. So we just check our work on the 110 DPI, 27 inch 2010 iMac at 2650x 1600. We prefer to not to get too complicated about this.

If it looks good on the iMac, it's going to look good as a print. Theorizing about why that's true seems pointless.

Last edited by normhead; 11-30-2018 at 12:48 PM.
11-30-2018, 11:31 AM   #57
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QuoteOriginally posted by TonyW Quote
The second and least appreciated (IMO) is DPI. A printers dpi specification is pretty meaningless in relation to the ejaculation (I have a dislike of the misuse of the word Giclee quite affected again IMHO!) of ink onto paper. The dpi specification is merely the pitch of the stepper motor usually seen as two figures in the specs. I do not think in terms of dots either because the printer 'squirts' ink onto paper and that volume of ink does not have a fixed size it will spread according to variable such as substrate absorption paper surface type and many other factors...It can take many DPI to form 1 PPI
Thank you for this note. The dot pitch is not a good indication of final result, though it may serve as a guide for appropriate photo resolution to avoid excessive and sloppy upsampling during printing. The jab at the term giclee was particularly fun.


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11-30-2018, 11:33 AM - 1 Like   #58
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QuoteOriginally posted by photoptimist Quote
At some level, your editing might improve because a 4k 15.6" display with the image set to 100% will actually give you a very good idea of how the image will look printed at 300 ppi. At that resolution some of the pixel-peeping artifacts you would have edited on a low-res display at 100% might be invisible (as they would be invisible on the print) so you won't be tempted to waste time editing them.

But if you are addicted to pixel peeper editing, then you'll need to go to to 200% or 400% to magnify the artifacts.

If you have (or can get) a 4k TV and your new laptop has an HDMI port, then there's a good chance you could mirror or extend the desktop to the TV. The TV would act as a larger monitor that shows you more of the image.
QuoteOriginally posted by TonyW Quote
^^ This ^^
Yep...


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11-30-2018, 11:36 AM   #59
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QuoteOriginally posted by normhead Quote
If it looks good on the iMac, it's going to look good as a print. Theorizing about why that's true seems pointless.



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11-30-2018, 11:57 AM - 1 Like   #60
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Well this should be controversial if nothing else (not posted for that reason) may stimulate discussion at the least. Below is a recommended viewing distance based on visual acuity and basically pixels density. Mainly aimed toward UHD 4K display but just as relevent to any. This shows a 15" unknown monitor to my 24" ColorEdge. These figures are IMO quite sound and may be taken as a guideline. At this time I will say that they are actually based as well on THX standards for enjoying TV again based on visual acuity that has been bandied around by most of us here.

I no longer need to work to ISO standards or indeed follow DICOM (medical Imaging) standards for anything including image viewing distance and tbh am unsure if these standards vary from those shown in this graph. If pushed I will seek them out to see if there are any other recommendations. If anyone knows of them please point to the link it would be nice to see what if anything has changed

I am quite prepared to offer back up of the thinking and maths behind this but do not think that it required at this time I can confirm that these are real world figures - use or not, accept or not your call

Last edited by TonyW; 04-30-2019 at 12:12 PM.
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