February 6, 2007 4:00 AM PST

Why increase pixel counts?

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More megapixels, better photos: Fact or fiction?

February 6, 2007
There are advantages to increasing the number of megapixels. Larger prints that require a minimum pixel count can be easier to make and consumers can crop images to focus on just the subject matter they want.

But there are costs, too. Among the more obvious burdens: camera image-processing chips have more data to digest, memory cards and hard drives fill up faster, and photo editing puts greater space, memory and time demands on computers.

More subtle problems also are possible. Camera image sensors rarely get larger from one generation to the next, so squeezing more megapixels out of a sensor means each pixel on the sensor is smaller. In most of the chip business, smaller electronics are dandy, but with cameras, they translate to less light per pixel.

That light difference means it's harder to distinguish the signals produced by light from the electronic noise in the sensor. The idea of making the signal-to-noise ratio worse may sound pretty technical, but possible consequences are easily understood: images suffer from color speckles and cameras work poorly in dimmer conditions such as indoors.

"If you try to cram more pixels into the same amount of space, you risk getting signal degradation because you're not getting as much light into the same pixel," said Chris Crotty, an analyst with iSuppli.

It can be tough for consumers to understand why they might not want to snap up the most megapixels possible. "People can understand the idea of more numbers is better," Crotty said. "But signal-to-noise, fill factors, dynamic range, blooming--these are concepts most people aren't going to understand."

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4 comments

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Thank you!
I really wish more people would take notice of this.

People don't understand that there are more metrics than just MP in evaluating a digital camera, so they vote with their wallets for the cheapest, highest MP cameras possible.

The result is that digital cameras use very small CCD sensors (<a class="jive-link-external" href="http://www.dpreview.com/learn/?/key=sensor_sizes" target="_newWindow">http://www.dpreview.com/learn/?/key=sensor_sizes</a>) to take huge but poor quality pictures that will need to be compressed before they are used for anything anyway.

The Digital SLR cameras have larger sensors (and are better for low light, and and moving subjects) but they are still $800 and the larger sensors are slow to make their way into cheaper cameras because the buying public does not understand the metrics used.

Given that many consumer digital cameras on the market now take crappy photos that are ~ 5 meg in size I would expect that now would be as good of a time as any for manufactures to improve other areas but MP race does not look to be ending any time soon.

I refuse to pay $800 for a digital SLR that will work well in low lighting, so I bought a Cannon Rebel 35 mm SLR for cheap and when I get my pictures developed they scan the negatives onto a CD for free.

I am going to keep doing it this way untill digitals start shipping with larger/better quality sensors and are goot at more than just MP.

I am willing to bet there will be people walking around with cameras that take 40 meg photos using 8x7mm sensors long before that ever happens.

It is so bad that even many people that sell digital cameras for a living don't realise that there is more to a camera than just the MP count.

If you go to Walmart.com and look at cameras, the specifications for many cameras don't even bother to list the sensor size of the camera.

After all, why would the total amount of light a camera can capture when it takes a photo be important to the picture quality?

You would think cameras work by capturing light or something.

I have 2 digital cameras, sometimes when I take photos indoors I can hear the shutter taking longer than a full second to capture enough light for the picture. This pretty much ensures than any low light pictures taken without a tripod come out crappy.

This huge problem with digital cameras tends not to show up in professional reviews (like here on CNET), because cameras are tested using tripods, still objects, and studio lighting.

Perhaps maybe if the professional reviewers add in a metric for "moving object in low light setting" it may raise awareness by giving low marks to cameras that perform poorly here.
Posted by Dachi (797 comments )
Reply Link Flag
RE: Thank you!
If you want a good place to get info on the latest cameras, check
the following link.

<a class="jive-link-external" href="http://www.steves-digicams.com/" target="_newWindow">http://www.steves-digicams.com/</a>

He has the most comprehensive reviews I have found.

As for great pictures, my 30 year old Olympus OM-1 still takes
better pictures than just about any digital camera under $1,000,
but I need to get back into developing my own film again. :-)
Posted by protagonistic (1868 comments )
Link Flag
Thank you!
I really wish more people would take notice of this.

People don't understand that there are more metrics than just MP in evaluating a digital camera, so they vote with their wallets for the cheapest, highest MP cameras possible.

The result is that digital cameras use very small CCD sensors (<a class="jive-link-external" href="http://www.dpreview.com/learn/?/key=sensor_sizes" target="_newWindow">http://www.dpreview.com/learn/?/key=sensor_sizes</a>) to take huge but poor quality pictures that will need to be compressed before they are used for anything anyway.

The Digital SLR cameras have larger sensors (and are better for low light, and and moving subjects) but they are still $800 and the larger sensors are slow to make their way into cheaper cameras because the buying public does not understand the metrics used.

Given that many consumer digital cameras on the market now take crappy photos that are ~ 5 meg in size I would expect that now would be as good of a time as any for manufactures to improve other areas but MP race does not look to be ending any time soon.

I refuse to pay $800 for a digital SLR that will work well in low lighting, so I bought a Cannon Rebel 35 mm SLR for cheap and when I get my pictures developed they scan the negatives onto a CD for free.

I am going to keep doing it this way untill digitals start shipping with larger/better quality sensors and are goot at more than just MP.

I am willing to bet there will be people walking around with cameras that take 40 meg photos using 8x7mm sensors long before that ever happens.

It is so bad that even many people that sell digital cameras for a living don't realise that there is more to a camera than just the MP count.

If you go to Walmart.com and look at cameras, the specifications for many cameras don't even bother to list the sensor size of the camera.

After all, why would the total amount of light a camera can capture when it takes a photo be important to the picture quality?

You would think cameras work by capturing light or something.

I have 2 digital cameras, sometimes when I take photos indoors I can hear the shutter taking longer than a full second to capture enough light for the picture. This pretty much ensures than any low light pictures taken without a tripod come out crappy.

This huge problem with digital cameras tends not to show up in professional reviews (like here on CNET), because cameras are tested using tripods, still objects, and studio lighting.

Perhaps maybe if the professional reviewers add in a metric for "moving object in low light setting" it may raise awareness by giving low marks to cameras that perform poorly here.
Posted by Dachi (797 comments )
Reply Link Flag
RE: Thank you!
If you want a good place to get info on the latest cameras, check
the following link.

<a class="jive-link-external" href="http://www.steves-digicams.com/" target="_newWindow">http://www.steves-digicams.com/</a>

He has the most comprehensive reviews I have found.

As for great pictures, my 30 year old Olympus OM-1 still takes
better pictures than just about any digital camera under $1,000,
but I need to get back into developing my own film again. :-)
Posted by protagonistic (1868 comments )
Link Flag
 

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