Posted: Sun Mar 13, 2011 7:47 pm Post subject: Resolution
I know the resolution is at 72 PPI at default. And when i change the PPI but keep the same.. say 4x4 Image, it increases in size. I guess what im asking is, is it wise to change the resolution for a 4inch by 4inch image from 72 PPI to a different resolution.. What i want to do is optimize how the image looks without changing the size.
Sorry if this is a stupid question but I'm new to all this.
Joined: 05 Mar 2003
Posts: 3987
Location: Cheltenham, UK
Posted: Mon Mar 14, 2011 4:48 am Post subject:
It all depends on your intended output medium. Resolution will vary according to your final usage. _________________ If life serves you lemons, make lemonade!
Joined: 26 Nov 2010
Posts: 368
Location: Australia
Posted: Mon May 23, 2011 7:56 pm Post subject:
I'm using your question to get this right in my own head! Here's how I think it works (somebody correct me if I'm wrong).
The total number of pixels in your document remains the same (unless you do some "stuff" to it). So:
- If you display it at 72ppi, it means that you are fitting 72 pixels side by side in a 1 inch wide row. This spreads the pixels out and makes the document look big.
- If you display it at 300ppi, it means that you are squeezing 300 of your pixels into the same one inch row. This squashes the pixels together and makes the document look small.
So the number of pixels, and hence the image size, remains the same. But you can output it "small and dense" (good for a printer) or "big and loose" (fine for a monitor).
UNLESS... you tick the box which says "resample image". If you resample the image you will gain or lose pixels.
If you resample and make your image smaller, you are downsampling, which is more common than making it bigger. Making it bigger is called upsampling. You would downsample before putting a large image on to the web. To upsample, pixels need to be "made up" from somewhere. There are different methods used for resampling, each with their own pros and cons (e.g "Bicubic").
To "optimize how the image looks without changing the size" (I assume that you mean file size) you first need to choose whether to optimise for screen or optimise for the printer. You would also have to untick the "resample image" box. If you want to display it on a screen, 72ppi is fine. If you want to output to a printer then it set it to 180ppi or more.
Hope that helps. Sorry if it's confusing. If you play with image->image size and then view->print size you'll get a feel for it.
You cannot post new topics in this forum You cannot reply to topics in this forum You cannot edit your posts in this forum You cannot delete your posts in this forum You cannot vote in polls in this forum You cannot attach files in this forum You cannot download files in this forum
