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reducing MPs
If you reduce res in order to increase number of shots by how much worse do the photos become? How much different is "fine" from "normal" anyway? Next down is "economy". Thus, is keeping at 6mp using economy better than using 4mp with fine? My 4mp camera produces 500kb pics at fine, but photos look just as good as a 6mp at 4mp at fine which are 1mb...

Comments (12)

What are you doing with your photos? Print them? Email them?.

Hard drive space and memory cards are cheap your best bet is to shoot at the highest resolution. You can always make a photo smaller. Its a lot harder to make a small photo bigger..

You wont notice a quality difference if your only looking at them on your monitor or sending them in emails. You will notice it in prints up to a point.Compression removes data from your photo..

If this is no big deal to you shoot at what ever size and compression settings you like..

I did this once when memory was 200 dollars for 128mb and now I'm upset I did because I have some nice photos I can not take past a 4x6. But with todays cameras going from 12mp down to 5mp is not a big deal as long as you stay in the lowest compression setting (fine/high). Do not go lower then 5mp if you want to print 8x10, if you want larger prints stay at the highest res. Why buy a high res camera just to turn it down..

Sparky_caGo take photos ..

Comment #1

You could invest a dollar and get five prints made, all of the same subject, each shot at a different resolution..

You probably wont see any difference on a 4x6 print, down to 2 MP..

The bigger the print, the great the difference, but again, not much difference on an 8x10 print until you get to 3MP and below..

Most countertop labs (wal-Mar, etc) let you enlarge the middle of pictures that result in 5x7 prints, so you can get a 5x7 print for under a dolar that shows what would be just part of an 11 x 14 shot..

BAK..

Comment #2

If your camera has a decent downsizing image, you can typically reduce the pixel count to 64% of the rated MP for the sensor..

The simple fact is that most cameras making JPEG images have about 80% less actual resolution than is implied by the sensor's pixel count.8 x .8 = .64 or 64%.

So with an 8Mp camera, you can save 5Mp images with only super subtle image quality differences or losses in detail. With a 10Mp camera, 6Mp would do similarly..

When you do this you might find that you can apply less in-camera sharpening since sharpening is often applied after the image is downsized..

I ran a blind test a while back using an 8Mp DSLR. I posted image pairs and asked people to identify which had been downsized in-camera and then resized to 8Mp. The Olympus camera I used can output different pixel counts from the same raw..

The net result was interesting. About half of the total guesses were right and about half wrong. So on average, people couldn't tell which was which. But there were a handful of people who got it 100% correct and also 100% wrong. And upon close, pixel peeping examination, you can start to pick up on subtle clues that show the difference. But that should tell you something.

So as a practical matter, if your camera has decent internal processing, you can reduce to about 64% with little fear of losing detail..

Here is a link to that test if anyone is interested..

Http://forums.dpreview.com/...forums/read.asp?forum=1022&message=20651503.

Jay Turbervillehttp://www.jayandwanda.com..

Comment #3

What will be the effect if reduced from fine jpeg to normal? I know this will almost cut the file into half. very useful if running out of flash card...

Comment #4

Victor beato wrote:.

What will be the effect if reduced from fine jpeg to normal? I knowthis will almost cut the file into half. very useful if running outof flash card..

Words such as "fine" and "normal" are specific to each manufacturer, and also vary from cameras to camera. For EXAMPLE, Olympus has used terms such as SHQ, HQ and SQ to describe the different settings. There was an interesting comparison done some time ago here:http://www.wrotniak.net/photo/c5050/c5050-comp.html.

The results suggest that even the lower quality jpeg (at full resolution) is acceptably good, and very hard to distinguish from the best quality jpeg..

Where things become less simple is in post-processing. Say you have an image which is a little bit too dark, so you use an image editor to brighten it. The lower-quality jpeg will probably not be satisfactory when adjustments are made, showing artefacts and lack of true detail in the shadow areas and so on, compared to the best quality jpeg..

So in an emergency when running out of card space it acceptable to use a lower quality (jpeg compression) setting. But memory cards are so inexpensive these days, it is wise to just buy more cards than you think you need.Regards,Peter..

Comment #5

Victor beato wrote:.

What will be the effect if reduced from fine jpeg to normal? I knowthis will almost cut the file into half. very useful if running outof flash card..

The effect is dependent on HOW the camera manufacturer performs JPEG. The JPEG specification is incredibly broad! Like most international organizations, it allows all members to do pretty much what they want. It is also difficult to summarize so that "beginners" can understand it. There is some complex mathematics involved..

All cameras and photo editing software pick a few out of the billions of possible JPEG settings. They call these names, acronyms, and numbers that will hopefully imply the correct things to users. Unfortunately, some of the number schemes are backwards from other number schemes!.

Calvin Hass (a dpr member) has a free JPEG utility, called "JPEGsnoop". It allows us to actually SEE the differences in our JPEG pix. His site also explains the JPEG format..

Http://www.impulseadventure.com/photo/jpeg-snoop.html.

I can assure you that you won't understand most of this at first! But given some time and effort, you can sorta understand what is going on..

Calvin also makes an attempt to quantify the level of accuracy in the lossy compression JPEG schemes. He calls this a "Quality Factor" and it is associated with the Quantization Tables. You can use these "Quality Factors" to approximately define the difference in the various choices on your camera..

I recommend that you download the latest version of JPEGsnoop and support what Calvin is doing. There is a huge database of information about how various cameras and editors encode JPEG. If you find that your camera is not in the database, it's easy to upload your data. This will keep expanding the database..

Finally, the visual effects of these various JPEG schemes are hard to quantify. In general, JPEG is very good (optimised) for encoding continuous tone photos. It's less good for handling high contrast images like printing. It also can show visible artifacts in monotone areas, like the sky. If you use the highest quality/lowest compression level setting for your camera, it should be virtually impossible to see any compression artifacts. As you downgrade the quality setting, small artifacts start appearing, but this is often dependent on the type of image you are recording..

Charlie DavisNikon 5700, Sony R1, Nikon D300HomePage: http://www.1derful.infoBridge Blog: http://www.here-ugo.com/BridgeBlog/..

Comment #6

Finally, the visual effects of these various JPEG schemes are hard toquantify. In general, JPEG is very good (optimised) for encodingcontinuous tone photos. It's less good for handling high contrastimages like printing. It also can show visible artifacts in monotoneareas, like the sky. If you use the highest quality/lowestcompression level setting for your camera, it should be virtuallyimpossible to see any compression artifacts. As you downgrade thequality setting, small artifacts start appearing, but this is oftendependent on the type of image you are recording..

That's why I recommend downsizing 64%, but using a high quality compression scheme. You can save space and essentially lose almost no detail..

Of course, always shoot some test photos before relying on any change in procedure with important photos..

Jay Turbervillehttp://www.jayandwanda.com..

Comment #7

A nice discussion. Like they say "I needed that"ThanksKenny..

Comment #8

Victor beato wrote:.

What will be the effect if reduced from fine jpeg to normal? I knowthis will almost cut the file into half. very useful if running outof flash card..

Useful and cut by half, yes, but by how much is the quality worse? by half?that was what I asked 1st...

Comment #9

Sherwoodpete wrote:.

So in an emergency when running out of card space it acceptable touse a lower quality (jpeg compression) setting. But memory cards areso inexpensive these days, it is wise to just buy more cards than youthink you need.Regards,Peter.

300 pics at 3mb is 900mb. Thats more than a CD-R on just one shoot!.

Lowering to 1mb saves downloading time, saves card space, and unless making prints seems acceptable...

Comment #10

And if you shoot low and you want to crop, you're screwed..

Comment #11

Just buy some more cards, and shoot at the highest resolution...

Comment #12

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This question was taken from a support group/message board and re-posted here so others can learn from it.

 

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