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Re: [OM] at the limits of my maths

Subject: Re: [OM] at the limits of my maths
From: Chuck Norcutt <chucknorcutt@xxxxxxxxxxxxxxxx>
Date: Fri, 06 Nov 2009 03:36:32 -0500
What Moose said.  You cannot be given a size (like 120 cm) and a pixel 
dimension (like 1024) and also given a resolution value (like 80 ppi) 
since the first two determine the third.  If the size is 120 cm and the 
pixel count is 1024 then the pixels per inch is already known at 21.7 
ppi (per Moose's calculation below).

Chuck Norcutt


Moose wrote:
> Fernando Gonzalez Gentile wrote:
>> And no, I'm not smiling.
>> Perhaps because it's too late at night and I should be sleeping instead. I'm 
>> facing a resize problem, both using CS3 or SIPro2.
>>
>> .tif is at 4000 ppi, width 3,39 cm., height 2,28 cm. pixel dimensions: width 
>> 5341, height 3594.
>>
>> I'm required to resize it to with 120 cm. and 1024 pixels wide.
>>
>> Resolution must be no less than 80 ppi - stubbornly I had been insisting in 
>> 300 ppi.
>> But cannot solve this at 80 either.
>>   
> 
> As presented, the problem cannot be solved. 120 cm = 47.24 in. 1024 
> pixels divided by 47.24 in. = 21.7 ppi. The specs are simply incompatible.
> 
> Whoever has posed this problem to you has something wrong, or you have 
> copied it wrong. There is no reason on earth to make such a request.
> 
> PPI is meaningless except when printing. Even then, all printer drivers 
> or RIPs are perfectly capable of correctly adjusting the pixels to match 
> the desired printed image size, without any math or resampling on your 
> part. The results will generally be more optimal than any resizing you do.
> 
> Are you sure you aren't already asleep  - and dreaming impossible problems?
> 
> Moose
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