Image Content issues vs Output Needs


McGregNi

Link Posted 22/06/2013 - 15:13
This is an offshoot topic coming from the 'K5II vs s Choice Considerations' thread. I want to split it here because this relates to any camera, not just the K5 models - I want to keep the other thread for the testing and comparison matters specifically. But this printing stuff is important and related.

I want to clear up any misunderstandings about what I mean when I'm trying to consider suitablility for large printed output. It has to be understood that none of these processed images are having their dimensions or resolution altered. The 16Bit TIFF remains at the full pixel sizes and number of total pixels after each processing step. The adjustments to sharpness and details being made are not altering the total amount of image data in each shot - that remains the same amount as the camera sensors captured originally. But these image dimensions are not the only concern when deciding how big a print can go.

Here's a way to think about the considerations to make - say you have a nice portarait shot, but there's a slight bit of movement blur. You get a 5'x7' print made, and up close you can see the blur a bit, but put it on the bookshelf and everyone who passes says 'what a great shot!'.
So you order a big enlargement of it.

The online software recognises your max quality JPEG as having sufficient pixels (the dimensions x resolution) to produce an 'optimum' print at your chosen huge size. Great! Order it. Massive! But, when it arrives, sure, there's a lovely big colourful and smooth looking print - but the face looks out of focus, and now its a really big face, and the blurring has ruined it. The blurring has got bigger along with everything else. Waste of money!

So, you see that its not just about what specifc magnification or resolution a shot can tolerate to be successful at any particular print size - its actually about the image content, and the inherant 'quality' of that actual content as well. That is the issue I am exploring in relation to image content as captured by the 2 K5II models. How the content stands up to the processing needed to optimise clarity and detail (depending on type of shot - eg commercial product shot or beach snapshot) before any negative effects of this needed optimising becomes distracting and ruins it when printed big.

You have to factor in the image content, its latent 'quality', what is needed to optimise the presentation of the content that it will stand up to inspection at the large size, and how far you can go before any processing artifacts become too distracting that you can no longer consider such a big output. This is what my print considerations are all about over on the other thread
My Guides to the Pentax Digital Camera Flash Lighting System : Download here from the PentaxForums Homepage Article .... link
Pentax K7 with BG-4 Grip / Samyang 14mm f2.8 ED AS IF UMC / DA18-55mm f3.5-5.6 AL WR / SMC A28mm f2.8 / D FA 28-105mm / SMC F35-70 f3.5-4.5 / SMC A50mm f1.7 / Tamron AF70-300mm f4-5.6 Di LD macro / SMC M75-150mm f4.0 / Tamron Adaptall (CT-135) 135mm f2.8 / Asahi Takumar-A 2X tele-converter / Pentax AF-540FGZ (I & II) Flashes / Cactus RF60/X Flashes & V6/V6II Transceiver
Last Edited by McGregNi on 22/06/2013 - 15:14

johnriley

Link Posted 22/06/2013 - 15:29
The K-5 offers an output of approximately A3 at 300ppi. This can be extrapolated up or down in Photoshop to provide the optimum file for any print size we like. It will stand upscaling to quite some degree, and of course downscaling is also possible.

The K-5 II and IIs offer similar sizes as standard.

Yes, it applies equally to all cameras. Make the file the right size for the print or web and you'll get the optimum result.
Best regards, John

McGregNi

Link Posted 22/06/2013 - 15:53
johnriley wrote:
Make the file the right size for the print or web and you'll get the optimum result.

Only if you're not thinking about the 'quality' of the content. That is really what this is all about, and indeed any content 'optimization' differences required by the different cameras depending on how much of the detail any specific size reveals to the eye.
My Guides to the Pentax Digital Camera Flash Lighting System : Download here from the PentaxForums Homepage Article .... link
Pentax K7 with BG-4 Grip / Samyang 14mm f2.8 ED AS IF UMC / DA18-55mm f3.5-5.6 AL WR / SMC A28mm f2.8 / D FA 28-105mm / SMC F35-70 f3.5-4.5 / SMC A50mm f1.7 / Tamron AF70-300mm f4-5.6 Di LD macro / SMC M75-150mm f4.0 / Tamron Adaptall (CT-135) 135mm f2.8 / Asahi Takumar-A 2X tele-converter / Pentax AF-540FGZ (I & II) Flashes / Cactus RF60/X Flashes & V6/V6II Transceiver

gwing

Link Posted 22/06/2013 - 16:01
My lazy-man way to get an idea of how large a print I can reasonably do from an image is just to zoom in on screen until the apparent image size matches my intended print size and view it at that size. Holding a physical print next to the screen to judge both zoom level and how far away from the screen I should be viewing from helps as well.

I don't ever like to have print drivers interpolating my work so I always upscale my image to intended output size at the printers native resolution, or an exact multiple of that anyway, and it is really surprising how much you can push this process for large prints. Viewing that resultant huge image to assess image quality is in theory what I should be doing but its a lot of faff - the above lazy way works for me and is quick.

McGregNi

Link Posted 22/06/2013 - 16:14
gwing wrote:
My lazy-man way to get an idea of how large a print I can reasonably do from an image is just to zoom in on screen until the apparent image size matches my intended print size and view it at that size. Holding a physical print next to the screen to judge both zoom level and how far away from the screen I should be viewing from helps as well.

I guess there's some similarities there to how I'm judging the shots, but of course the point is that on the other thread the actual image content is being adjusted to try and reach limits and make judgments depending on what's seen.
My Guides to the Pentax Digital Camera Flash Lighting System : Download here from the PentaxForums Homepage Article .... link
Pentax K7 with BG-4 Grip / Samyang 14mm f2.8 ED AS IF UMC / DA18-55mm f3.5-5.6 AL WR / SMC A28mm f2.8 / D FA 28-105mm / SMC F35-70 f3.5-4.5 / SMC A50mm f1.7 / Tamron AF70-300mm f4-5.6 Di LD macro / SMC M75-150mm f4.0 / Tamron Adaptall (CT-135) 135mm f2.8 / Asahi Takumar-A 2X tele-converter / Pentax AF-540FGZ (I & II) Flashes / Cactus RF60/X Flashes & V6/V6II Transceiver

Pentaxophile

Link Posted 22/06/2013 - 16:26
Nigel, I understand what you're getting at here. It's not about the method of resizing a shot for print (or whether it's worth bothering at all - Siskin press say 'just give us the original size and let our printers handle the scaling!')

It's about whether there is blur, or lens artefacts, or noise, that limit the potential acceptable size of the print.
[link=https://500px.com/will_brealey/[/link]
Last Edited by Pentaxophile on 22/06/2013 - 16:27

johnriley

Link Posted 22/06/2013 - 16:51
Yes, but it's pretty obvious that for a high quality larger print you need a high quality image to start with.

Let's not over-complicate it.
Best regards, John

Pentaxophile

Link Posted 22/06/2013 - 16:58
Nigel was talking about the image content issues not how to scale the image to print.

It may be obvious but it is a separate issue to the photo resizing topic, which has been done to death before
[link=https://500px.com/will_brealey/[/link]
Last Edited by Pentaxophile on 22/06/2013 - 17:00

gwing

Link Posted 22/06/2013 - 17:48
Pentaxophile wrote:
Nigel was talking about the image content issues not how to scale the image to print.

It may be obvious but it is a separate issue to the photo resizing topic, which has been done to death before

Yes, but they are sort of connected.

If you just send to your printer 'as is' and let them print to size there really isn't any reference, other than actually ordering the print, to judge what it will look like or for Nigel to assess what quality would be like at that size.

However if you expand to print resolution yourself and then also view at that size it does provide a way of making a quality assessment without the expense of printing. Perhaps it's not as good a way as having the print in your hand but it's the next best thing.
Last Edited by gwing on 22/06/2013 - 17:51

McGregNi

Link Posted 22/06/2013 - 18:03
Pentaxophile wrote:
Nigel was talking about the image content issues not how to scale the image to print.

It may be obvious but it is a separate issue to the photo resizing topic, which has been done to death before

Exactly, thanks! That's why I moved it over to here to be discussed independently, because on the K5II comparison thread I didn't want people to think I am worrying about printing quality matters in relation to the resolution of the image that is 'sent to the printer'. My comparison thread is not about that at all - there's no comparison there because the pixel dimensions and ppi resolution is exactly the same for each pair of images being compared.

I am not adjusting the image resolutions or dimensions - I find them perfectly OK as they are at 4928x3264, 300x300dpi, Bit Depth 48, Uncompressed, File Size 92.1mb.

I don't think printers will have too much trouble with that, even with max quality JPEGs (mine are 17mb). We have high quality images 'out the can' with these cameras, so talk of extrapolating and upscaling really is over-complicating it.
My Guides to the Pentax Digital Camera Flash Lighting System : Download here from the PentaxForums Homepage Article .... link
Pentax K7 with BG-4 Grip / Samyang 14mm f2.8 ED AS IF UMC / DA18-55mm f3.5-5.6 AL WR / SMC A28mm f2.8 / D FA 28-105mm / SMC F35-70 f3.5-4.5 / SMC A50mm f1.7 / Tamron AF70-300mm f4-5.6 Di LD macro / SMC M75-150mm f4.0 / Tamron Adaptall (CT-135) 135mm f2.8 / Asahi Takumar-A 2X tele-converter / Pentax AF-540FGZ (I & II) Flashes / Cactus RF60/X Flashes & V6/V6II Transceiver

johnriley

Link Posted 22/06/2013 - 18:12
The concept of resizing is very important Nigel and not at all complicated.

Just use the crop tool and put the figures you want in. This is described in the six articles for beginners that I wrote for PU, see the articles section of the site.
Best regards, John

McGregNi

Link Posted 23/06/2013 - 15:23
Pentaxophile wrote:
Nigel, I understand what you're getting at here. It's not about the method of resizing a shot for print (or whether it's worth bothering at all - Siskin press say 'just give us the original size and let our printers handle the scaling!')

It's about whether there is blur, or lens artefacts, or noise, that limit the potential acceptable size of the print.

Yes, that's my point I am not trying to dismiss the importance of resizing - I understand it can be necessary for certain print requirements. But like Pentaxophile, it is never an issue when I send shots 'to the printers' - ie: uploaded to a commercial website printer. It seems that so long as there is enough pixel data, it is their own processes that will produce the right fit for the chosen print size. They just offer some guidance to the likely quality - such as 'optimum', 'good', 'fair'.

As my example in the opening post suggested, the concern I have in comparing the 'content' of the K5II & 's' versions, is at what size will any artifacts caused by the extra detailing / sharpening etc needed on the K5II image become a distraction and deter from the perception of 'high quality'.

This point is determined by the following variables - how big the print -how far away will it be viewed from - and elements within the image content. So it is a decision to be made individually for each shot.
My Guides to the Pentax Digital Camera Flash Lighting System : Download here from the PentaxForums Homepage Article .... link
Pentax K7 with BG-4 Grip / Samyang 14mm f2.8 ED AS IF UMC / DA18-55mm f3.5-5.6 AL WR / SMC A28mm f2.8 / D FA 28-105mm / SMC F35-70 f3.5-4.5 / SMC A50mm f1.7 / Tamron AF70-300mm f4-5.6 Di LD macro / SMC M75-150mm f4.0 / Tamron Adaptall (CT-135) 135mm f2.8 / Asahi Takumar-A 2X tele-converter / Pentax AF-540FGZ (I & II) Flashes / Cactus RF60/X Flashes & V6/V6II Transceiver
Last Edited by McGregNi on 23/06/2013 - 15:23

McGregNi

Link Posted 24/06/2013 - 12:58
gwing wrote:
If you just send to your printer 'as is' and let them print to size there really isn't any reference, other than actually ordering the print, to judge what it will look like or for Nigel to assess what quality would be like at that size.

However if you expand to print resolution yourself and then also view at that size it does provide a way of making a quality assessment without the expense of printing. Perhaps it's not as good a way as having the print in your hand but it's the next best thing.

I'm nearly finished with the comparisons over on the other thread - there should be some firm conclusions over there in the next day or two.

Just to tie up the loose end on this printing question, I wanted to clarify things and see others views on the 'resolution' issue. Ever since the 's' model was announced there was talk of the extra 'resolution' it would offer. I was a bit confused by this, as I was thinking of resolution purely in pixels per inch terms (eg 240ppi, or 300ppi), and when multiplied by the pixel dimensions this would give you the total amount of pixel data.

It is these deimension and ppi figures which are exactly the same for both cameras (they have the same sensor). So I have avoided referring to the effect of less blurring on the 's' image as 'higher resolution', as I feel this confuses it. Keeping the termonolgies distict (resolution & blurring) means I do not think of the 's' image as having a higher 'resolution' - I don't see that it does.

As print output is determined by resolution and dimensions, this means that the potential printed output max size is the same for both cameras.

I am not comparing that as there is no comaparsion as I see it. Nothing I have done in adjusting the shots has altered the dimensions or ppi density.

The question is about how much work is needed on any particular image, depending on content, to make it look 'sharp enough' at your chosen size before any negative results or srtifacts are made big enough to detract from the the overall quality.

Rob, I'd like to ask specifically what you mean by 'expand to print resolution and then also view at this size...' - if I can do this more exactly it may help me.
My Guides to the Pentax Digital Camera Flash Lighting System : Download here from the PentaxForums Homepage Article .... link
Pentax K7 with BG-4 Grip / Samyang 14mm f2.8 ED AS IF UMC / DA18-55mm f3.5-5.6 AL WR / SMC A28mm f2.8 / D FA 28-105mm / SMC F35-70 f3.5-4.5 / SMC A50mm f1.7 / Tamron AF70-300mm f4-5.6 Di LD macro / SMC M75-150mm f4.0 / Tamron Adaptall (CT-135) 135mm f2.8 / Asahi Takumar-A 2X tele-converter / Pentax AF-540FGZ (I & II) Flashes / Cactus RF60/X Flashes & V6/V6II Transceiver

Pentaxophile

Link Posted 24/06/2013 - 13:47
I think what gwing means is you can change the document size to whatever size you intend to print, and then view at 'print size' on the computer screen.

You can then also send it to the printer - untick 'fit to page' and you can print a 4x6" test print of part of the image to see what the quality is like at A3, A2 or whatever. (I tried this with a hypothetical A1 size image from the K7, and bearing in mind the viewing distance of a large print, was very pleased!)
[link=https://500px.com/will_brealey/[/link]

gwing

Link Posted 24/06/2013 - 14:16
Quote:

Rob, I'd like to ask specifically what you mean by 'expand to print resolution and then also view at this size...' - if I can do this more exactly it may help me.

Rather than just zoom the image to a larger size onscreen you can resample and upsize the image itself to the much larger print size and then apply your final sharpening and image assessment at that resolution. Most comprehensive photo programs provide this facility (certainly photoshop, gimp and darktable do), there is usually a quality/speed tradeoff in the resampling according to the algorythm you choose and, if you are doing a really big size expansion, you can perhaps get better results by doing successive smaller ratio resizes than one big one.

It could be that the crop tool will also do this automatically if it has 'resample' and ppi options.

As an example, if I wished to print my image at 30x20 on an Epson inkjet with native 720ppi resolution I would resample my image to 21600x14400. Actually I wouldn't as that's a big file, I would probably do it at 360ppi giving a x4 smaller file but still giving the Epson print driver a simple integer scaling job but you get the idea. There are many folks that say this whole upsampling thing is not worthwhile of course so I'll state that now to avoid your thread getting completely derailed
Last Edited by gwing on 24/06/2013 - 14:19
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