Can’t reduce pixel amount yet keep image dimensions

RS
Posted By
Ryan_Swift
Nov 29, 2008
Views
358
Replies
8
Status
Closed
I’m using CS3 on Windows XP.

I can’t work out why some of my A4 documents (210mm x 297mm at 300dpi) are at pixel size 3600 x 8910 (using about 160M) and others are at 2480 x 3508 (using 33M).

They’re all in CMYK and use 8 Bit/Channel.

I can’t find any way of reducing the pixel amount in the larger files, and subsequently the memory used.

What am I missing?

Thanks,
Ryan.

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DM
dave_milbut
Nov 30, 2008
at pixel size 3600 x 8910 (using about 160M) and others are at 2480 x 3508

because the 2 different size images are at different resolutions, if they both print out the same size.

here’s the 1st one:
< http://www.pixentral.com/show.php?picture=1t36dgJQfuklllXCdp zFnaKq3DAk0>

here’s the 2nd:
< http://www.pixentral.com/show.php?picture=1VinaJ8frxQvTBCWxQ GCucdKOao7H>

see the diff in mm in the screen shots? my guess is, if they BOTH print out at 210mm x 297mm, then the 1st one is set for 300ppi, and the 2nd one is set for something else.

open one of each, hit image> image size, and check the resolution box.
DM
dave_milbut
Nov 30, 2008
oops… plugged the wrong #s in the 2nd example… here it is: < http://www.pixentral.com/show.php?picture=1rVSVfyHXzTwvy1z2D boVgvptfJIM1>
DM
dave_milbut
Nov 30, 2008
to get the 2480 x 3508 image to print at 210mm x 297mm the ppi would be set to: ~300ppi.

to get the 3600 x 8910 to print at 210mm x 297mm the ppi would be set to (checking…) well, something else. that pixel dimension won’t lead to a 210mm x 297mm at any resolution without distorting the image. 🙂
DM
dave_milbut
Nov 30, 2008
and sorry, i’m trying to think in mm instead of inches. 😉

maybe i’m missing something, what do you mean by "using about 160M" and "33M"
RS
Ryan_Swift
Nov 30, 2008
Cheers for replying.
Your reply has helped me spot the problem – as I was checking the dimensions I noticed that the error was that one of my documents was at 300 pixels/inch and the other was 300 pixels/cm (putting it at 762dpi!)

No wonder it was at 160 meg!

Cheers again. 🙂
DM
dave_milbut
Nov 30, 2008
cool. i knew i wasn’t hitting it exactly, but i was hoping you would spot it!

762dpi!

yes, that’s what i was seeing (well, ppi is the correct term, not dpi, that’s a printing term ;)), but i didn’t think that could be right! 🙂

cheers back at you!
dave
JS
James_Sawyer
Nov 30, 2008
Thanks Dave, that was really helpful!
DM
dave_milbut
Nov 30, 2008
🙂

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