DPI Recommendation for Images

[Alan T Litchfield]

My immediate reaction was, read the archives. This topic has been  
rehashed many, many times in the past years.

However, upon reflection the proposals beg a question (from me  
anyway). Why do you think you ought to be able to dictate what level  
of zoom the reader will be using in whatever pdf reading software they  
are using? The considerations posed by Shane a pertinent and are  
strengthened with the concept of the pdf being a multi-platform/device  
file format.

There is no value that I see in trying to dictate to the reader what  
they will see at any specified zoom. The reader will decide what is  
`good enough' for their viewing pleasure.

You build the file according to whatever standards you consider  
appropriate. You can't really do any more than that.

Cheers
Alan

On 23/03/2011, at 7:28 AM, Shane Taylor wrote:

> Also consider whether your audience will be viewing the PDF on a  
> Windows, Mac, Linux, or UNIX machine, because the zoom level to  
> match monitor pixels will vary based on the system DPI setting (and  
> possibly the PDF viewer).
>
> Since we couldn't provide a consistently optimal viewing experience  
> for users across platforms, we decided to use 150 DPI because that  
> provides good print output (as a factor of most printer DPI  
> capabilities).
>
> Shane Taylor
>
>
>
> On Mar 22, 2011, at 1:13 PM, Joseph Lorenzini wrote:
>
>> Hi all,
>>
>> I'd like to get people's opinion on what they think is the best  
>> choice for DPI. Right now I import images into FrameMaker at a DPI  
>> of 144. This means that the PDF must be zoomed to 150% if the image  
>> pixels are to match the monitor pixels (i.e. it would be like  
>> zooming it to 100%).  However, I set the default zoom in the PDFs  
>> to 125% because I thought that 150% was just too big and  
>> overwhelming in a PDF. This means that the images look degraded.  
>> I'd like to improve this.
>>
>> As I see it, I have two options.
>>
>> (1) In FrameMaker, I could change each image's DPI to 120. This  
>> means that the image would NOT look degraded in a PDF at a zoom  
>> level of 125%. The drawbacks are two fold: 1) I have an enormous  
>> amount of documentation and it would take a considerable amount of  
>> time changing the DPIs for each image though I suspect there may be  
>> a plugin out there that could automate this process for each book.  
>> 2) Images would be noticeably bigger and take up more space in the  
>> documentation.
>>
>> (2) I could set the default zoom in the PDFs to 150%. The upside to  
>> this is that its a very trivial change. The downside is that the  
>> PDFs would be enormous. On a monitor resolution of 1200x1600 it  
>> looks big but ok, whereas on 1024x768 I find it to be too large to  
>> be readable. Admittedly, I am assuming that most users in a  
>> corporate environment would have monitors with a maximum resolution  
>> of 1200x1600 but I don't know for sure.  Plus, not everyone likes a  
>> res that high.
>>
>> So what say you all? Which option do you favor and why? And of  
>> course, if there's another option I haven't thought please let me  
>> know.
>>
>> Thanks,
>> Joe

--
Alan T Litchfield
AlphaByte
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New Zealand
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