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Old Jan 24, 2004, 8:01 PM   #1
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Default An infernal dilemma

Hi all ... just found this place and signed in .... I have to now describe this dilemma ... please bear with me.

Fact #1 ... I have worked with amages for years .. and most work is web oriented .... hardly ever print.

Fact #2 .. first digcam was a Casio, ages ago ... adequate - just. But it did give me pics at 150 dpi even if optics not good and very few options. Camera #2 . Kodak DX6340 .. excellent for what it is ... shoots at 230 dpi but ... not enough facilities re manual control .... and optics maybe not quite adequate. Now trying a Minolta IiMAGE Z1 ... great facilities but ... horror ... only shooting at 72 dpi.

Fact #3 ..... for me 72 dpi just will not cut it .. way too pixilated .. and highlight diagonals look like a staircase!!

So - I have been looking around and find that these days even up to ''prosumer'' level .. 72 dpi seems to be called an ''industry standard''. Well fine I guess if you want to print posters from an 8 MPix camera .. but for use on web .. no good for me.

OK, I know monitor res' is less than what I want but ... appearance is what matters and as said .. 72 dpi just don't cut it.

I don't ideally want to go spending a fortune on high level SLR's if avoidable (and still want to know dpi figures but no one seems to quote them!) ..... plus, altho I used film SLR's and interchangeable lenses in old days as freelance .. I now really want the sort of spec that the Minolta offers ... or the Sony DSCF 828 too ... with fixed lens but good optical zoom .. and masses of manual control .....

BUT ....... at 150 dpi or better.!!

So - guru's out there who may know the market ... what can you suggest?? I do not need a zillion MPix ''resolution'' (terrible use IMO of that word) ..... I want true pixel resolution re pixel density . that's what matters.

Remember film?? Resolution was in lines/mm ..... now THAT is resolution .. and akin to my need for pixel density. Get the picture??

Please give me some thoughts if you would.
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Old Jan 24, 2004, 11:23 PM   #2
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Default Re: An infernal dilemma

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Originally Posted by ChrisB
for me 72 dpi just will not cut it .
The dpi value is just an arbitrary figure embedded in the file, and is irrelevant to the image data. It's *pixels* that count. You can turn the alleged 'dpi' figure up & down and it will make no difference to the print quality, provided you supply the printer driver with a print size.
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Old Jan 24, 2004, 11:46 PM   #3
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DPI (or more accurately PPI) is only relevant when you know the resolution. A 4000 X 3000 image at 72ppi will yield an image of 13.3 inches by 10 inches at 300ppi. This is more than sufficient for a photo quality image.
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Old Jan 25, 2004, 12:30 AM   #4
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DPI has no meaning whatsoever until the image is printed. An image that is 2000x1500 pixels @72DPI is identical to one "resized" to 2000x1500 pixels at 300DPI. Until it is printed: one will be 27.78"x20.83", the other will be 6.667"x5".

As you should know, they will be identical when viewed via the web.
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Old Jan 25, 2004, 6:45 AM   #5
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Chris B. .........The only figure that matters is what the camera produces as a data file and you can get that from the camera manual for each mode you select.

The common '72dpi' figure is a figure used for pc monitors and is scaled back from the original image to fit a whole image on your screen like zooming out. It has nothing to do with what the camera captures, so in future when you see this just think ..ah autosize my larger image detail to fit my PC screen, but it doesn't change my camera original image.

Printers do the same thing say at 300 dpi or higher. If your camera captures more than your printer or monitor, then these devices limit the resolution and more camera Mpix will not give you more. Capture with less than your printer or monitor needs then it's the camera that limits output resolution.

One day you might get fed up looking at pics on a monitor and like the look of 10x8 prints. Then you may wish you captured your image using a camera with more Mpix and good enough to get a decent sharp print.

You can always reduce resolution in software if a camera gives more data than you need - but you can never add more if there was insufficient resolution to start with. With film you didn't think about it so much because lenses were more the limiting factor than the film itself.

When you talk about pixelation and jaggies I think you are confusing what a video card is presenting and the PC monitor is capable of at its setting. I can downsample a 4Mpix image to lower than 320x240 and see what you mean, - the fault is not the camera, but what I told the software to do!

In terms of what you need, 2Mpix should be plenty for just web work with most PC setups. However, all the other factors like zoom, macro, dynamic range, good colour, low light, noise etc will make some difference, even for web pics. These things may get better in higher Mpix cameras, but only because that's the way new and better models are going.

I got used to looking at old VHS moviecam pics on my TV. But when I see them played on a new larger hi-res flat panel or compare with a high Mpix digicam still, I'm disappointed and I can't go back and re-shoot! VOX
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Old Jan 26, 2004, 3:01 PM   #6
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Guys,

Many thx all for input ... I didn't get an auto-notification so only sqaw the posts when checkin in.

I take your various points but .. I think either I did not explain well enough or some miss my point. Bear with me and I'll try and explain more

If for my web use I decide to shoot at 640x480 and 72 PPI . it will quite probably be almost ''ready to go'' without too much need for processing.

However ... that 72ppi is my starting pixel density .. I cannot make it higher .. the old rule - ''you cannot add what was never there'' applies. I am ''stuck'' with that 72. Now as I said .. printing out is of little importance - and I accept the Mpix aspects commented on if printing was my thing.
I really need to illustrate this with some pics ... it appears I can post images here so will try and demonstrate with something soon.


Think of film and ''lines/mm'' - which was true image resolution. For my needs, pixel density serves the same purpose ... even accepting the res of monitors as a limiting factor. The bottom line is ... a pic on the screen is way ''smoother'' at 150 ppi or better.

Don't go away .. I will take a coupla pics on different cameras .... and post them soon - one uses 230 ppi and the other 72ppi.

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Having a job to find best example and the time to do it!! For the time being let me add this .... I usually shoot a larger pic than needed .... so it is archived suitable for the rare event of printing. I usually downize (bi-cubic interpolation usually, occasionally linear) .... from say 2000 pix to 600 .... and this is where often the difference shows up.

A diagonal highlight will look smoother usually in the reduced higher pixel density pic then the 72 .. where ''pixilation'' is more apparent - the ''staircase'' effect I mentioned.

Seems I may have to get used to this 72 .... but high end pro cameras do I am sure still offer greater pixel densities, as well as high Mpix figures ..... but the ''pro-sumer'' and below all now seem to be the 72.

Oh one other thing .... if, even with a max macro shot, I need to crop in to a large pic to achieve the greatest effective ''magnification'' ..... again the higher pix density scores, cos I have better pix resolution to permit that.

OK .. enough rambling!! But leaving aside the various considerations ..... if anyone actually knows of a high end camera giving better than 72 ... I'd be most interested .....
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Old Jan 26, 2004, 3:37 PM   #7
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Quote:
Originally Posted by ChrisB
... If for my web use I decide to shoot at 640x480 and 72 PPI . it will quite probably be almost ''ready to go'' without too much need for processing.

However ... that 72ppi is my starting pixel density .. I cannot make it higher .. the old rule - ''you cannot add what was never there'' applies. I am ''stuck'' with that 72. ...
No - you are stuck with 640x480 pixels. You can change the ppi setting to anything you want with no change whatsoever to the image. Changing the ppi figure will neither add nor subtract from the information in the image. 72ppi is nothing more than a number used to fill an empty slot in the EXIF data in case some application needs it. It makes no more difference to the quality of your image than recoding GPS location data in the memo field of your EXIF data does.
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Old Jan 26, 2004, 7:36 PM   #8
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Thx for getting back again Bill .... I see your point.
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