JPEG resolution question


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Dec 27, 2009
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Hi All,

I have a question regarding picture resolution, hope you guys can help :)

currently using the 450D with 18-55 kit and saving pictures in Fine Large format. while zooming into the pictures for some PP, i realise that the pictures were not sharp at all. so upon checking the file properties, i found out that pictures taken with the 450 is only 72ppi, even though the dimension is 4272x2848.

i compare with pictures taken with a canon 8M powershot, and the pictures taken with the P&S powershot is much sharper than the 450D, at 180ppi!!!

did i miss out some settings on the 450? :sweat:
 

weikiat

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Jan 14, 2010
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why do u care about ppi?

do u even understand what it is?
 

Jed

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The slightly less brusque answer would be...

Go do a little research on what dpi/ppi means. Those figures are not relevant when viewing images on your computer screen, or if you have the same overall image dimensions in terms of pixels (ie a 4000x3000 image is always higher resolution than a 3000x2000 image, for example).

When you view on your monitor screen then you are generally viewing at a resolution of about 100 dpi/ppi (depending on your monitor size and resolution).

It's all a little difficult to explain in a couple of short paragraphs, but there's bound to be plenty of information out there. Suffice to say if your images aren't sharp then the problem probably lies elsewhere - camera, camera settings, photographer.

Good luck.
 

Rashkae

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Nov 28, 2005
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Suffice to say if your images aren't sharp then the problem probably lies elsewhere - camera, camera settings, photographer.

Good luck.
Fully agree. Also, you may have missed the whole point of a DSLR... It's to give the photographer flexibility. Compact cams have high sharpening settings by default, on a DSLR you have the power toadjust as you want to.

Or, of course, you may not know about aperture, depth of field or chosen the wrong focus point.
 

Reportage

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Nov 24, 2008
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actually why are you using jpeg?

since you are a new user, should start with raw and only jpeg once you know what you are doing.
 

Octarine

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#7
currently using the 450D with 18-55 kit and saving pictures in Fine Large format. while zooming into the pictures for some PP, i realise that the pictures were not sharp at all. so upon checking the file properties, i found out that pictures taken with the 450 is only 72ppi, even though the dimension is 4272x2848.
72dpi is the resolution of your screen and most viewers will show this. The problem of sharpness has been addressed by Rashkae. Post an image and let us see. Otherwise it's just guessing about many possible reasons for unsharp images.
Secondly: how much are you zooming in? At 100% you will see the first effects of jpg compression, further zooming will show unsharp images even with the high-end cameras. No point going beyond sensor resolution.
 

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Octarine

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actually why are you using jpeg?
since you are a new user, should start with raw and only jpeg once you know what you are doing.
Funny .. yes, overload the newbies with more technical stuffs. Can RAW save a screwed composition? JPF Fine is ok as starting point.
 

Dec 27, 2009
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actually why are you using jpeg?

since you are a new user, should start with raw and only jpeg once you know what you are doing.
reportage, maybe i am wrong, my concept is to get my composition, exposure, learn TV and AV etc right 1st before i move on to raw. would rather spend more time on taking pictures than processing it at the moment :) unless its studio/model, then i will take raw.

72dpi is the resolution of your screen and most viewers will show this. The problem of sharpness has been addressed by Rashkae. Post an image and let us see. Otherwise it's just guessing about many possible reasons for unsharp images.
Secondly: how much are you zooming in? At 100% you will see the first effects of jpg compression, further zooming will show unsharp images even with the high-end cameras. No point going beyond sensor resolution.
understand, thanks octarine.

Funny .. yes, overload the newbies with more technical stuffs. Can RAW save a screwed composition? JPF Fine is ok as starting point.
hahaha its ok, the best way to learn how to swin is to be thrown into the sea. ;p

thanks madmartian! :)
 

Dec 27, 2009
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#11
Fully agree. Also, you may have missed the whole point of a DSLR... It's to give the photographer flexibility. Compact cams have high sharpening settings by default, on a DSLR you have the power toadjust as you want to.
hi rashkae, think you are right, i've missed the whole point of a dslr... thanks for the reminder on why i got it in the 1st place, rather than chase after pixels! :D

The slightly less brusque answer would be...
hi jed, thanks for the explanation. think i have a wrong concept on ppi ;p i thought the more pixel there is in an inch, the 'sharper' it would be lol
 

Jed

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#12
hi jed, thanks for the explanation. think i have a wrong concept on ppi ;p i thought the more pixel there is in an inch, the 'sharper' it would be lol
You are absolutely correct per inch, all other things being equal (ie the image has to be sharp in the first place).

But a 1" x 1" image at 1000dpi has exactly the same detail as that image at 10" x 10" at 100dpi - 1000 pixels by 1000 pixels.

Your camera doesn't shoot in inches, it shoots in pixels. So you produce the same file and your resultant dpi is down to your end product size.

FWIW, very few monitors these days display at 72dpi, as I said the figure is close to 100 these days but the exact figure will depend on... your screen resolution and screen size (same concept again).
 

Octarine

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hahaha its ok, the best way to learn how to swin is to be thrown into the sea. ;p
Not really. It's a good concept for ending the swimming lesson very soon. Even with swimming skills you might be lost in the current. So better go step by step :) - After all it's a hobby, not a competition or run for life and death.
 

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