What good is a high MP count...

jesseyoung83 wrote:

... when the majority of photos are viewed online at sub-1000px sizes?

I understand that it's useful if you want to print them, but let's just assume that only a tiny sliver of photographers actually do this.

What I'm curious about is how big of an improvement, say, a 20MP image resized to 1000px will look compared to a lower MP image, like a 4MP from an older Sigma.

First of all, 1000px is not really what you need going forward.  As many displays move to a higher DPI you start to require 2x or so the resolution, so 2000px...

Lots of resolution means you can crop a lot more things out of an image.

Also, it means high ISO shots look great at smaller sizes because noise is reduced.  If you are just talking 1000px uses the SD-1 is an OK ISO 6400 camera.

For more arguments in favor of high resolution, consult the sidebar:

http://forums.dpreview.com/forums/post/50873573

With the higher MP count, you can crop the file. Some purists don't like to crop, getting their framing perfect I guess in the field, but many find the ability to crop useful. Think about bird, animal, wildlife photographers. Or if you're using a fixed prime lens....

I always felt I didn't really have enough MP with the DP1/DP2 (or SD14/SD15) to crop much, but I do with the resolution of the DP2Merrill (or my Canon 5DII) For the Canon,  cropping/straightening is really easy in its Canon software DPP. I wish Sigma's SPP had a crop/straighten tool.... In fact, how I usually crop or straighten a Sigma file is by saving it as a TIFF, then doing the crop in the DPP program! I tend to get my horizons crooked...

Best regards, Sandy
http://www.pbase.com/sandyfleischman (archival)
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jesseyoung83 wrote:

Good question!

And ... for most people on this planet the answer is .... none. Its not better at all. It might be so for you also. You dont print and only does sub 1000 pixel digital images. Hmmm ... yeah ... you dont need the latest Foveon, or any multi mega pixel camera at all.

Or ... maybe you do?

There is more information in a sharper image. With that information you can do things.

You have already been told you can crop. Lets say you have taken a land or cityscape. And then you see something far away or simply an interesting detail. You zoom in an see .. only pixels. Oops .. should have more of those things, then maybe I could have made an image of the detail.

But ... thats not the only thing. There are lots of manipulations where lots of pixels is a benefit. And ... there is also the feeling of security when you have too much. And ... for some reason ... images with many pixels has a tendency to look better IMHO.

Then, of course, you might not care about technical excellence, but its rather the content that is the main thing. Nothing wrong with that of course.

jcollier wrote:

I'm afraid that if you find it necessary to ask the question that you will not be enlightened by the answer.

Perhaps if you had understood the question a little better you would not have replied so rudely.

Many people feel that the push for more megapixels is a marketing gimmick for most people.

I think that a good 6mp camera would satisfy almost all of the needs of an amateur photographer.  I have produced school graduation quality portraits cropped about 50% from a original Canon 300D file, and it looks fine as an 8X10.  I am very happy with 11X14 prints from my Pentax 100D even cropped by around 30%. I say this from the perspective of someone who used a Leica M3 and a Rollei35 for 35 years before going digital, so I have some idea about quality in a print.

Of course, more mp is theoretically better but in almost all real life situations it doesn't make that much difference for non-professional photographers, especially if you are just viewing pictures on a computer.

PrebenR wrote:

<...>

But most important is the resolution and that you can work on a photo in post.

I forgot to mention that aspect - if you want to fix perspective after the fact having a lot of resolution means your eventual end image looks better at relatively high resolution, as you always lose some pixels in fixing distortion.

More pixels generally means more all around flexibility.

jesseyoung83 wrote:

But my main point of interest is in how bicubic downsampling algorithms utilize higher MPs, and the quantitative differences between resizing a huge image, like one from a Nikon D800, and a moderately sized one, like one from a Canon S100. The question is purely technical.

Thats also an interesting question.

Bicubic tends to result in a somewhat low local contrast.

I have never been all that interested in making optimal downsamplings.

Some here have better experience than me with that.

When I got my SD1 I tried comparing it to my SD15, using images downsized to HD (1920x1080).

I could barely tell any difference, but it seems to me that the SD1 images looked a slight bit better. This might be entirely psychological however.

Now we are seeing in-camera lens distortion correction and for this the more megapixels the better, because any kind of post processing that stretches or compresses any part of an image will compromise resolution in that area. Fortunately we are not seeing this sort of thing being done in-camera in any Sigmas yet. Personally I prefer the distortion to the loss of detail. With high megapixel counts the camera tries to remove the distortion without loss of detail, and I guess in the corners it is ok because we don't usually expect too much out at the edges.

I would like to be able to turn this feature off in those cameras that have it, but that's a firmware change driven by popular demand, and the demand just isn't there yet.

When I do a 19"x13" print, I want as many megapixels as possible, to take maximum advantage of all the resolution the optics can provide (or not). Looks like the DPxM series accomodates these needs the best so far (none of the vagarities of the SD1 vs lens, etc). I don't own a DPxM yet, but I'm moving in that direction.

High MP user is going to work in RAW, expects to do some PP manipulation beyond cropping slightly, and may be delivering a large size print image. 90% of amateur users don't need that 36MP. 12 MP or 18 MP is fine if you are printing at 8" x 11" or smaller, or displaying images on any monitor available now.

High MP users probably shoot mostly landscape, fashion, or architectural subjects.

Intermediate MP pro users will be the PJs and sports/ wildlife shooters. They want highest possible fps and top AF, which isn't going to happen with a 36 MP camera. 12 to 18 MP is fine.

NancyP wrote:

High MP user is going to work in RAW, expects to do some PP manipulation beyond cropping slightly, and may be delivering a large size print image. 90% of amateur users don't need that 36MP. 12 MP or 18 MP is fine if you are printing at 8" x 11" or smaller, or displaying images on any monitor available now.

I really don't know about that. In the wedding business we consistently print at 20" x 30" - and more - way more than that using 12MP from the Nikon D700. Plus D7000 and D90 cameras. And I have no trouble printing at 20" x 30" from Sigma SD14 & SD15 files.

High MP users probably shoot mostly landscape, fashion, or architectural subjects.

Intermediate MP pro users will be the PJs and sports/ wildlife shooters. They want highest possible fps and top AF, which isn't going to happen with a 36 MP camera. 12 to 18 MP is fine.

jcollier wrote:

I understood the question and my response was not intended to be rude.

My apologies if I misunderstood your tone.

My point was simply that a decent older camera with lower pixel count is capable of making prints that would please most enthusiasts most of the time.  A lot of people get sucked into the marketing hype and upgrade when it really won't make any difference to their pictures.

jesseyoung83 wrote:

... when the majority of photos are viewed online at sub-1000px sizes?

I understand that it's useful if you want to print them, but let's just assume that only a tiny sliver of photographers actually do this.

Cameras giving high quality images are currently most suitable for photographers who do want to make high quality prints.

In a few years, there will be 8k monitors in the shops, and people will also be able to view high resolution images on screen. You may want to future-proof your photos by taking shots now that will not look too outdated in 2120.

What I'm curious about is how big of an improvement, say, a 20MP image resized to 1000px will look compared to a lower MP image, like a 4MP from an older Sigma.