300dpi at under 1MB

Dolby

Dolby

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I took photos of few artists performing ... and they want 300dpi and 1MB each.

I know resizing to a certain resolution - but how do I make it to the spec they want?
 
play around with resolution and compression. gonna be small though
 
Forgive me if I'm wrong, but surely dpi has nothing to do with file size. If I have a full size image, from 350D that's 3456x2304 pixels. By default it's at 72dpi, if I change that to 300dpi, the photo's still got the same resolution, and thus the same file size. If they want files less than 1MB they're going to lose quality. You either have to lower the resolution, or the quality level to get there. dpi's not going to make a difference, it only makes a difference when printing the files.
 
Changing dpi doesn't affect image size in terms of Mb, only the size it's displayed at or printed.

JPEG compression will affect it's actual data size though.
 
Gareth is correct about the filesize. The only thing that really gets affected is the actual size of the image. If the client wants to make prints, find out what size they what to print it at. 640x480 at 72dpi = 22.5cm x 17cm (313K). 640x480 at 300dpi = 5.5cm x 4cm (313K). So a picture from a digital camera at 1535x918 pixels or 13cm x 7.77cm @ 300dpi will be 1mb.
 
Dolby said:
I took photos of few artists performing ... and they want 300dpi and 1MB each.

I know resizing to a certain resolution - but how do I make it to the spec they want?
Click to expand...
As mentioned DPI is a printer resolution. Without knowing the physical size they want to print it at there are just too many variables especially when you take compression into account. For example, depending on the image itself, I can export a full res 10mp image at 6/12 quality and it will come in under 1mb. Open that file in photoshop and you've got a 8"x12" print at 300dpi.

BTW - by them saying they want 300dpi it's a pretty clear indication they want to print these images - how much are they paying you?
 
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Resize to less than 1Mb size. Go into PS and manually change DPI to 300. Client happy. :)

The Myth of DPI

Many people seem to get hung up on the DPI (dots per inch) or PPI (pixels per inch) setting within a digital photo as a measure of the quality of those photos. To set the record straight, the DPI/PPI setting in a digital photo has NOTHING to do with digital image quality! The resolution of a digital image is its pixels (usually expressed as megapixels).
Click to expand...

link

What Print Shops Really Want

In a nutshell, what any print shop really wants is a digital image of sufficient pixel dimensions to be able to meet their required pixels per inch requirement (usually 300 ppi) at the dimensions of the printed image. The latter is critical, to find out if your image meets their ppi criteria, you have to know the destined printed size. For example, using the 300 ppi criteria, if the image is to be printed 8 inches in size, then your digital image has to be a minimum of 2,400 pixels in that dimension - it's simple arithmetic (2400 pixels / 300 ppi = 8 inches).
Click to expand...

link

more...

Misunderstandings about DPI
 
I have Irfanview now ...

I'm still battling :/

I go image > resize ... and select 'half' - but it comes at 350k.
If I select pixel 2500 - it's around 500k.

Surely both these options should be half?

Btw - now I'm trying to keep under 3MB, but I'd like to get as close as possible
 
Dolby said:
I have Irfanview now ...

I'm still battling :/

I go image > resize ... and select 'half' - but it comes at 350k.
If I select pixel 2500 - it's around 500k.

Surely both these options should be half?

Btw - now I'm trying to keep under 3MB, but I'd like to get as close as possible
Click to expand...

Have you tried LightRoom? You can download the trial for free.

Once you have processed your image in the "develop" module, right-click on the image, select "export". There you can choose JPEG output, with a specified file size. You can also choose to resize the image at the same time.
This is really the easiest way to hit a specific file size --- you can then play around with the resize factor to see which image size (in pixels) gives you the best-looking file at say 3 MB.

I am sure there are other software packages that can do the same, but LightRoom definitely makes this specific task a snap.
 
I don't have Irfranview but if you select half is it halving the horizontal and vertical resolution?
If so that would mean the new image would be 1/4 of the original resolution not 1/2 resolution.

Image resolution = Horizontal pixels * Vertical pixels
So a 3000 x 2000 pixel image = 6 Mega pixels
A 1500 x 1000 pixel image = 1.5 Mega pixels (not 3 Mega pixels)
2121 x 1414 = 3 Mega pixels
 
Dolby said:
I have Irfanview now ...

I'm still battling :/

I go image > resize ... and select 'half' - but it comes at 350k.
If I select pixel 2500 - it's around 500k.

Surely both these options should be half?

Btw - now I'm trying to keep under 3MB, but I'd like to get as close as possible
Click to expand...
Do a save as and select the desired file size.
 
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