Image sizes....

[Tom_G]

Hi all,

Been playing around with photoshop and Im just wondering;

What image size do people generally use to save their pictures when its just intended to be viewed in high quality on a monitor (15") (perhaps the odd occasional TV screen (32"). With resolution being the important factor obviously, I understand 300dpi to be a good place to start for high quality. But.. it creates quite a large file so im just wondering what compromise between the two do people generally go for.. and then what pixel dimensions would you use.. Iv no idea how big 3xxx X 2xxx will be unfortunately...??

Thanks,

Tom

[RobDickinson]

Forget dpi its meaningless until you print.

IMO anything over 1080 (1920x1080) is too big.

Most monitors are maxed out at 1000px or so high.

But most places frown on images over 1000ish px longest edge, I usually do portrait ones smaller, 800 or 900.

[14-7]

I shoot in RAW and always save the RAW file, a modified file as a photoship file (for editing), a full size JPEG and then a 900 pixel wide JPEG (or long depending on which is greater).

The 900 wide (long) files are the ones I upload to FlickR and on my 22 inch monitor always look fine.

[RobDickinson]

Tom_G said:

Iv no idea how big 3xxx X 2xxx will be unfortunately...??
Thanks,

Tom

As above you can store and save copies in a smaller size.

But as for 3xxx by 2xxx.

The largest computer monitors are 2500x1500 or so, even big TVs are only 1920x1080.

More resolution is used for print or cropping.

[Simpo Two]

The pixels in the image translate to pixels on the screen. So if the image is 3000 x 2000px and the screen is 1500 x 1000px, you will see a quarter of the image. However pixel dimensions are less vital if the software scales it to fit the screen. If your TV doesn't do this, then make the image the same pixel dimensions as the TV. You may need to crop it top or bottom as the camera is probably 3:2 and the TV is 16:9 - aspect ratio. (Or the TV may auto crop or shrink to fit, dunno)

[andy-xr]

I have 3 file sizes - original RAW file, hi-res jpeg (ie in original resolution after edits) and resized jpeg for web at either 1200px on longest side or 800 px on longest side depending on who/what I'm shooting (for)

[flat-planedCrank]

andy-xr said:

I have 3 file sizes - original RAW file, hi-res jpeg (ie in original resolution after edits) and resized jpeg for web at either 1200px on longest side or 800 px on longest side depending on who/what I'm shooting (for)

Same here (but I store a high res TIFF rather than JPG )

[abarth500]

300dpi is a waste of time for screen., monitors can't display any more than 72dpi.

[Simpo Two]

abarth500 said:

300dpi is a waste of time for screen., monitors can't display any more than 72dpi.

My monitors run at the native resolution of 1280 x 1024 px. The horizontal dimension is 13.4", which according to my calculator makes 95dpi.



To see if I was going mad I had a quick Google:

'Since the 1980s, the Microsoft Windows operating system has set the default display "DPI" to 96 PPI, while Apple/Macintosh computers have used a default of 72 PPI.'

http://en.wikipedia.org/wiki/Dots_per_inch


But as already mentioned, dpi is of no concern - you can open the image in PS and make it any dpi you like, it just gets larger or smaller.

[abarth500]

I stand corrected, thanks for the link

[flat-planedCrank]

Increasing the DPI in doesn't effect the image quality in any way

Quick example:



One of these images is 300dpi, the other is 3dpi - they are the same image.

The image is essentially a series of values for the colour of each pixel (or dot) - DPI is basically just a number stored with that image to tell printers how many of those dots to cram into an inch. So changing that value doesn't actually effect the quality of the image.

If you want to change the DPI of an image in photoshop: Image Menu - Image Size - Untick 'Resample Image' - Change the DPI value to whatever you want - Press OK.


Hope this helps

[Tom_G]

Wow, thanks for the excellent responses all!

And apologies for not responding sooner... been away this weekend!

Off to have a little play with Photoshop now..

Tom