OK It’s sinking in now, phew, takes a bit of thinking to un-learn a concept, especially since my wife and co-designer works specifically with printable products and 300dpi… The extra step is literally just a couple of seconds in the re-sizing process, so I don’t really mind doing that to follow the standard being requested. I can now see why it is unnecessary for web purposes – it’s the pixel dimensions that dictate the file size. I think my confusion stemmed from misunderstanding the term “pixel dimensions” – I thought it referred to changing the size of the pixel itself. Looking back this does sound quite ridiculous since a pixel is physically fixed on the screen. Looking forward to trying to finally wrap my head around different pixel widths for video aspect ratio work…
graphicmind saidThats coz u changed the file size as well.
mrcharlesbrown saidI just tried changing a 4,018 KB file at 300 dpi to 72 dpi and you’re right but it became larger (4,027 KB). So it looks like 72 dpi results in larger files sizes
graphicmind saidIt does mate!
As far as I know dpi does not increase file size.
DPI (in print) and PPI (in digital devices) are the Quality of and image, BUT They are useful WHEN we’re creating an image by it’s “REAL DIMENSION ” (inches, Centimeters….)
DPI (PRINT) for exaple when you want to create a Business Card, you start a new document “10×5 cm” and then you give it a 300 DPI for print. you never notice the pixels… so in 300 DPI Photoshop automatically changes the pixels related to your DPI and your Real Dimension. now if you go too image size and try to change the DPI you will understand that the PIXELS are getting smaller or Bigger. it’s the quality you are setting for your document.
major print machines can not print files over 300DPI so that’s why we choose 300DPI as an standard for designing/printing documents. no need for more dpi.
PPI (pixels per inch)
as it says, pixels per inch.. it means that the quantity of pixels that fits in 1 inch on displays. it’s now your choice that the image is showing on a LCD screen or a Mobile screen.
an iPhone4 with retina display screen has 640×960 pixels, but all that pixels fits on a 5×7.5 cm Display, the same 640×960 pixels on a 19” LCD looks much bigger than on an iphone. that’s why it looks sharper on an iphone.
so when you are designing an icon for Digital Displays, number in PPI should be set for the specific device. then the ICON looks the same size in iphone and also the LCD .
please note that PPI and DPI called as RESOLUTION in image size window.
Hope this helps.
if you changed the DPI and you didn’t see any different it’s because the PIXELS are constant … the document size based on it’s PIXELS and then Layers / Styles ….
The whole 72 ppi (dpi) for web is a myth. I tested this myself just to prove a point to a silly developer who wouldn’t accept the fact he was wrong.http://photokaz.com/2012/06/image-resolution-irrelevant-web-display/