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02-16-2010, 09:06 AM   #1
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Detail and resolution from web photos.

I'm using an HP 8510w laptop with NVIDIA Quadro FX 570M, 256MB 512MB TurboCache, 15.4 inch WSXGA+ WVA (1680 x 1050 and 16M colors)

It's a three year old laptop, so many of you are likely to be judging the photos you see online with much finer screens and graphics utilities. Are most of you that are more than very casually into this hobby using much better monitors? The HP LP2475w - 24" - widescreen TFT active matrix LCD display has a 1900 x 1200 resolution which still only corresponds to 2.280 megapixels of info from your photos. And unless you're using the entire 24 inches to display the image border to border, it's even less.

Other screens....

800600 (SVGA – standard) 12″..............................0.48
1024768 (XGA – standard) 12″, 13.3″, 14″, 15″.......0.79
1280800 (WXGA – wide) 15.4″, 14.1″, 13.3, 12.1″...1.02
1440900 (WXGA+ – wide) 14″................................1.30
12801024 (SXGA – standard) 14″, 15″, 15.7″...........1.31
14001050 (SXGA+ – standard) 12.1″, 14″, 15″........1.47
16801050 (WSXGA+ – wide) 15.4″.........................1.76
16001200 (UXGA – standard) 14″, 15″, 16″.............1.92
19201200 (WUXGA – wide) 17″, 15.4".....................2.30

A 1280 x 800 screen, fairly common, is reproducing 1.02mp. The image is not usually viewed edge to edge so we can expect somewhat less than 1mp available to display the detail/resolution of any photo online.

I do understand, of course, the need to have 12mp of info in image files for the purpose of cropping and for producing the finest detail for printing or enlarged printing. But I often see pics on the web accompanied by something along the lines of "look at how sharp this photo is". My screen displays 1.76 megapixels of information. Unless someone identifies the photo as some percentage of a crop from the original, then doesn't it make little sense to comment on it's detail and sharpness? Isn't, for the purposes of comparison on average laptop screens, such an image incapable of displaying sharpness and detail beyond what a 2 megapixel camera is capable of delivering?

Is my thinking off on this? And if, on occasion, shooting images for the express purpose of web posting with no intention of crop or revision then should the camera's range be set to no more than 2mp?

(be kind... remember this is the beginner's section. i might even be off by a few decimal points!)


Last edited by frascati; 02-16-2010 at 09:58 AM.
02-16-2010, 09:27 AM   #2
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its not about the resolution

what you should be looking into are colour gamuts and dynamic ranges.

low grade monitors are very bright (good for text) but blow out highlights and make turn shadow detail into pure blackness.

i have a gaming monitor (TN) side by side with a 6 year old 19" VN type monitor, both from samsung.

the difference in photo quality is easy to distinguish.

have a read through this:

LCD Panel Technology Explained - S-IPS, H-IPS, S-PVA, MVA and TN

again, its not about RESOLUTION, its about panel-type, a feature that is seldom advertised by monitor manufacturers.




as for a relationship between high pixel photos and the web, i personally resize my RAW photo's manually using 3rd party programs (such as Photoshop) to web-levels (600X400 or smaller), often times the re-sizing algorithem of Photoshop is superior to browser based ones.. or even FaceBook, i always re-size myself for facebook, and people tend to comment on how pretty my photos look
02-16-2010, 12:07 PM   #3
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QuoteOriginally posted by frascati Quote
.. Unless someone identifies the photo as some percentage of a crop from the original, then doesn't it make little sense to comment on it's detail and sharpness? Isn't, for the purposes of comparison on average laptop screens, such an image incapable of displaying sharpness and detail beyond what a 2 megapixel camera is capable of delivering?
I was curious about this when I did a lens test last year. My question was, if I had two test photos taken with different lenses, viewed at 1000x667 pixels, could I see quality differences between them? I decided I could. Some cons:
  • It was not as easy as seeing a 100% crop comparison.
  • I used my desktop monitor, not a laptop
  • I had already seen the 100% versions and knew what to look for.

I don't think it's wise to make a final judgment on sharpness on any downsized photo. You don't know how it was downsized, whether the software automatically applied sharpening, etc.

QuoteQuote:
Is my thinking off on this? And if, on occasion, shooting images for the express purpose of web posting with no intention of crop or revision then should the camera's range be set to no more than 2mp?
It wasn't that long ago when the super-expensive pro models only had a couple of megapixels and everyone was OK with that. Probably the biggest reason we have more today is because it doesn't cost much more to have them. But even if images are only going to be on the web, you give up some advantages by starting at a lower resolution. On my camera, tt means giving up the adjustment range of shooting RAW. Storage is inexpensive, you never know what the future holds and it's easy to throw away pixels but hard to recreate them.
02-16-2010, 02:21 PM   #4
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The only place where I see that it makes sense to shoot at 2 megapixels is if you have no chance to down size your photos. The problem is really that there is no possible way to up size the information in your photo, so if by some freak of nature, you have shot a photo a 2 megapixels and decide it is good enough to (wonder of wonders) print, you are kind of stuck. However, it is very simple with photoshop to do a batch resize and resize images to 800 pixels across, or whatever works for you.

You are correct however that you are unlikely to see a difference in web size photos at much over about 2.5 megapixels (and probably a lot less than that).

02-16-2010, 07:51 PM   #5
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Web sites have also gone up in resolution, with people getting better screens. bandwidths have also gone up, as youtubes gone HD.

1024x768 is most standardized right now, who knows what the future may hold... never hurts to plan for the very future future.. you never know what your great grand children will be using (well some do).

Last edited by tokyoso; 02-16-2010 at 08:18 PM.
02-17-2010, 08:17 AM   #6
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I should have left off the last part about shooting at 2mp. The suggestions are all quite valid, and it should have been obvious to me anyway. Bytes are cheap nowadays, and you never know what you might want out of the image in the future.

It was the question of whether or not you can judge resolution above 2mp on current technology computer screens that I was most interested in. There really are a lot of photos on the web accompanied by exclamations on their detail and sharpness.
02-17-2010, 08:25 AM   #7
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QuoteOriginally posted by frascati Quote
I should have left off the last part about shooting at 2mp. The suggestions are all quite valid, and it should have been obvious to me anyway. Bytes are cheap nowadays, and you never know what you might want out of the image in the future.

It was the question of whether or not you can judge resolution above 2mp on current technology computer screens that I was most interested in. There really are a lot of photos on the web accompanied by exclamations on their detail and sharpness.
what do you mean "judge resolution"

resolution is static :/

unless you mean sharpness, then thats a whole different ball game

the point is though where the photo is going to end up, and who is going to see it from how far away...

you're really making it more complicated than it is

more MP = better

what your final output is depends on YOU, its really not that difficult to resize images..
02-17-2010, 09:21 AM   #8
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I'm not asking about my own images. I'm specifically referring to other's images posted to the web.

You might still be misapprehending what I'm asking.
I probably am missing something fundamental here that is making my question unclear.
A 1.76 mp screen is what I have to view an image with on this laptop. So it cannot render detail beyond 1.76 megapixels. Correct?

Never mind sharpness. I think i understand correctly that it is indeed a separate measure than resolution. Even low resolution images can be rendered more or less 'sharp'. I'm talking about detail. Whether or not the fine print on an image or a single hair on an animal is visible or not as a direct consequence of how many pixels are available either in the image or when reproducing it on screen.

8mp of info in an image is higher resolution that 2mp. More mp is better right? So in a side by side comparison, same lens, same setup, etc, of an image of a (distant) eye chart, the 8mp image is going to provide a resolution that renders more of the lines readable. Stop me where I'm wrong here (but don't get exasperated). But for the purposes of viewing both of these images and comparing them on a 1.76 megapixel computer screen, it is not possible to distinguish the superior 8mp detail/resolution. No?

I'm not talking about viewing my own images where I obviously have all the data available to feed the screen at any zoom/crop level. I'm talking specifically about the images that others provide via the web for purposes of comparative quality of detail. I know image compression methods can complicate this, and may potentially make the 8mp image worse due to an inferior compression method than the 2mp version rendered at 600x800 (for instance). But when both of these images are on my screen I don't think it's usually the case that I can continue to zoom on the "better" quality image to access it's superior level of information (detail). When I resize images appropriately for the web they are generally something like 600 x 800 or similar. That's all the information I've provided others have to judge it by.

I don't see how I'm overcomplicating this. Isn't it a very straightforward question?
To the point... someone puts up an image in a forum and says look at the fantastic detail and clarity (disregarding color, brightness, etc) of this shot. Generally they are saying look at the precision at which this lens was able to deliver the image to my 12mp sensor. But any of that fantastic precison that I'm trying to judge this lens upon is lost in translation to my 2mp computer screen. No?


Last edited by frascati; 02-17-2010 at 09:44 AM.
02-17-2010, 09:38 AM   #9
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QuoteOriginally posted by frascati Quote
You might still be misapprehending what I'm asking.
I probably am missing something fundamental here that is making my question unclear.
A 1.76 mp screen is what I have to view an image with on this laptop. So it cannot render detail beyond 1.76 megapixels. Correct?

Never mind sharpness. I think i understand correctly that it is indeed a separate measure than resolution. Even low resolution images can be rendered more or less 'sharp'. I'm talking about detail. Whether or not the fine print on an image or a single hair on an animal is visible or not as a direct consequence of how many pixels are available either in the image or when reproducing it on screen.

8mp of info in an image is higher resolution that 2mp. More mp is better right? So in a side by side comparison, same lens, same setup, etc, of an image of a (distant) eye chart, the 8mp image is going to provide a resolution that renders more of the lines readable.
Stop me where I'm wrong here (but don't get exasperated). But for the purposes of viewing both of these images and comparing them on a 1.76 megapixel computer screen, it is not possible to distinguish the superior 8mp detail/resolution. No?

I'm not talking about viewing my own images where I obviously have all the data available to feed the screen at any zoom/crop level. I'm talking specifically about the images that others provide via the web for purposes of comparative quality of detail. I don't know enough about image compression. But when both of these images are on my screen, and as long as they both have content above the number of pixels available to them on whatever portion of real estate they're using on my screen at the moment, I don't think it's usually the case that I can continue to zoom on the "better" quality image to access it's superior level of information (detail). When I resize images appropriately for the web they are generally something like 600 x 800 or similar. That's all the information that others have to judge it by.

I don't see how I'm overcomplicating this. Isn't it a very straightforward question?
To the point... someone puts up an image in a forum and says look at the fantastic detail and clarity (disregarding color, brightness, etc) of this shot. Generally they are saying look at the precision at which this lens was able to deliver the image to my 12mp sensor. But any of that fantastic precison that I'm trying to judge this lens upon is lost in translation to my 2mp computer screen. No?
personally, i would take a noiseless 1.76 MP image over a very noisy 8mp image, on a 2mp computer screen.
02-17-2010, 09:39 AM   #10
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*mubles into the air*

QuoteOriginally posted by frascati Quote
You might still be misapprehending what I'm asking.
I probably am missing something fundamental here that is making my question unclear.
A 1.76 mp screen is what I have to view an image with on this laptop. So it cannot render detail beyond 1.76 megapixels. Correct?
correct

however you can still enlarge/zoom in to your 8MP photo, discovering more detail, should you feel the need.

because if you view a 1.7mp photo on a 1.7mp screen, any attempt at zooming in will end up in a complete wash.

so trying to make out that license plate will end in failure.
02-17-2010, 09:39 AM   #11
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QuoteOriginally posted by tokyoso Quote
personally, i would take a noiseless 1.76 MP image over a very noisy 8mp image, on a 2mp computer screen.
the 8mp image will be down-sampled anyway....
02-17-2010, 09:46 AM   #12
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QuoteQuote:
however you can still enlarge/zoom in to your 8MP photo, discovering more detail, should you feel the need.

Is it me? Gooshin, are you deliberately trying to frustrate me? I stated, twice, with emphasis, that I'm not talking about having 8mp of information AVAILABLE TO ME!

QuoteQuote:
I'm not talking about viewing my own images where I obviously have all the data available to feed the screen at any zoom/crop level. I'm talking specifically about the images that others provide via the web for purposes of comparative quality of detail.
I'm talking ONLY about viewing other's images on the web.

Stop mumbling into the air, put your espresso down for a sec, and just read the entire original question.

QuoteQuote:
To the point... someone puts up an image in a forum and says look at the fantastic detail and clarity (disregarding color, brightness, etc) of this shot. Generally they are saying look at the precision at which this lens was able to deliver the image to my 12mp sensor. But any of that fantastic precison that I'm trying to judge this lens upon is lost in translation to my 2mp computer screen. No?

Last edited by frascati; 02-17-2010 at 10:03 AM.
02-17-2010, 09:54 AM   #13
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Like images of Actual Pixels must be compared to evaluate lens IQ differences. Convert from RAW to 16-bit TIFF, crop actual pixels section, then convert to jpeg, no brightness or contrast adjustments, no sharpen, no levels and no curves adjustments.
02-17-2010, 09:58 AM   #14
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down sampling a very noisy image may not always result in a noiseless image.

Downsampling to reduce noise, but by how much?: dpreview.com Editorial blog: Digital Photography Review
02-17-2010, 10:00 AM   #15
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You are absolutely correct. You cannot judge the resolution of a 14MP photo that fits into the display area of a normal monitor, assuming of course that its not way out of focus. Siimilarly unles you have a calibrated wide gamut reference monitor you cant tell much about dynamic range and colour depth either, though it may look "good" on some monitors.

A lot will also depend on the image ratio (dots per pixel). Images displayed at 100%, 50% or 25% resolution will always be sharper than those displayed at some intermediate fraction and will have far less aliasing. Its better to downsize and sharpen a photo and display it at 100% than to let windows resize it to fit.

You can perceive how much sharpening has been applied though. Thats just a factor of edge contrast - its not resolution dependent but many people think its the same.

Its also hard to tell the difference between most cameras on an A4 size print. You need A3 to easily distinguish a 12 from a 6MP image, and A2 to easily spot 24MP from 12MP.


QuoteOriginally posted by frascati Quote
I'm using an HP 8510w laptop with NVIDIA Quadro FX 570M, 256MB 512MB TurboCache, 15.4 inch WSXGA+ WVA (1680 x 1050 and 16M colors)

It's a three year old laptop, so many of you are likely to be judging the photos you see online with much finer screens and graphics utilities. Are most of you that are more than very casually into this hobby using much better monitors? The HP LP2475w - 24" - widescreen TFT active matrix LCD display has a 1900 x 1200 resolution which still only corresponds to 2.280 megapixels of info from your photos. And unless you're using the entire 24 inches to display the image border to border, it's even less.

Other screens....

800600 (SVGA standard) 12″..............................0.48
1024768 (XGA standard) 12″, 13.3″, 14″, 15″.......0.79
1280800 (WXGA wide) 15.4″, 14.1″, 13.3, 12.1″...1.02
1440900 (WXGA+ wide) 14″................................1.30
12801024 (SXGA standard) 14″, 15″, 15.7″...........1.31
14001050 (SXGA+ standard) 12.1″, 14″, 15″........1.47
16801050 (WSXGA+ wide) 15.4″.........................1.76
16001200 (UXGA standard) 14″, 15″, 16″.............1.92
19201200 (WUXGA wide) 17″, 15.4".....................2.30

A 1280 x 800 screen, fairly common, is reproducing 1.02mp. The image is not usually viewed edge to edge so we can expect somewhat less than 1mp available to display the detail/resolution of any photo online.

I do understand, of course, the need to have 12mp of info in image files for the purpose of cropping and for producing the finest detail for printing or enlarged printing. But I often see pics on the web accompanied by something along the lines of "look at how sharp this photo is". My screen displays 1.76 megapixels of information. Unless someone identifies the photo as some percentage of a crop from the original, then doesn't it make little sense to comment on it's detail and sharpness? Isn't, for the purposes of comparison on average laptop screens, such an image incapable of displaying sharpness and detail beyond what a 2 megapixel camera is capable of delivering?

Is my thinking off on this? And if, on occasion, shooting images for the express purpose of web posting with no intention of crop or revision then should the camera's range be set to no more than 2mp?

(be kind... remember this is the beginner's section. i might even be off by a few decimal points!)
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