Could someone clear this up for me - Digital dpi

Irish_Tom

Irish_Tom

Irish_Tom

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18 Oct 2002
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Lo all,

I've just started a Graphic Design Degree and my lecturer was telling us about the industry standard for print specifications etc. He mentioned that the print spec is 300dpi and suggested that anything we scanned in should be 300dpi. He also said that most Digital Cameras shoot at 72dpi and that they would need converting in photoshop to 300dpi.

Now, my Digital Camera (Olympus C-5000) shoots .tif at 144dpi but it's still not high enough. I also find that if I use photoshop to convert it to 300dpi it makes the images look worse.

I'm hoping to get a D50 for my Birthday and I was woundering if anyone could tell me if I can get 300dpi from it. Does .RAW shoot at 300dpi?
If it doesn't shoot at 300 should I expect the image quality to be so much better than my C-5000 that changing the res in Photoshop won't be an issue?

Cheers all

Panzer
 
Raymond Lin said:
how can it look worst? you are probably zomm in, it'll look pretty much the same with photoshop increasing the pixel count.
Click to expand...

Because interpolating is just educated guessing and cannot add any extra information?
 
I've never known a camera to output at anything other than 72dpi, whether in RAW or in any other mode.

I'd assume that yours is interpolating the results to fake a higher megapixel rating that it actually has (similar to the Fuji Super CCD) which is why results look rubbish on screen.

Also make sure that 'Resample Image' isn't selected when you are adjusting Resolution in Image Size but that 'Constrain Proportions' is.
 
Digital cameras don't actually use a dpi value for shooting.
The dpi only becomes relevant when you're printing.
A Nikon D50 shoots 6.1 megapixels ~ 3000 x 2000.
At 72dpi that resolution would have a size of 41" x 27", however a 6 megapixel 6" x 4" would be 500dpi.

On my Canon 20D, the RAW processing software allows me to select what dpi I want when converting to other image formats.
 
Well yes, technically speaking digital cameras just shoot at a certain resolution, but if you took a JPEG off your 20D it would open up as 72dpi.

RAW shouldn't have an attributed dpi value until you convert to another format, but I would have thought that TIFF would still keep the 72dpi...

Actually, I do recall reading something about Olympus cameras having a SHQ mode that outputs at 144dpi. Hmmm.
 
The figure of 72dpi is only a constraint imposed by most computer displays.

Screen pixels are completely different to and independent of image pixels. ie, if you view an image on the screen at the same physical size (eg, 6x4") as you want to print it at, you would not see all of the image pixel data, as the screen pixel is about 10 times the size of the print pixel. You can zoom in to view the detail (so that each image pixel maps exactly to a screen pixel), but the image on screen will appear much larger than the print version.
 
Tomsk said:
On my Canon 20D, the RAW processing software allows me to select what dpi I want when converting to other image formats.
Click to expand...

For me its the 350, but the software does the same thing. Huge files though when we starting talking 350dpi!
 
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