Author Topic: Resolution change  (Read 5771 times)

Offline Roger Caris

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Resolution change
« on: June 30, 2009, 07:56:43 AM »
When I use Tools mask/umask to mask exif data PM changes the resolution of the jpegs from 300ppi to 72ppi. How can I mask exif data and keep the resolution to 300ppi?






Version 4.5.4 WinXP 64X 8GB RAM Canon 5Dmkii originally CR2 files

Offline Kirk Baker

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Re: Resolution change
« Reply #1 on: June 30, 2009, 08:26:16 AM »
Roger,

When I use Tools mask/umask to mask exif data PM changes the resolution of the jpegs from 300ppi to 72ppi. How can I mask exif data and keep the resolution to 300ppi?

The DPI setting is stored in the EXIF data.  By masking the EXIF data your preference is lost.  You really can't have EXIF both masked and visible at the same time.

-Kirk

Offline Roger Caris

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Re: Resolution change
« Reply #2 on: June 30, 2009, 09:21:37 AM »
As I mask the EXIF data I understand the preference is lost and I assume that it then goes to a default setting of 72ppi.

If this is what happens is it possible for me to change the default setting to 300ppi?

Offline Kirk Baker

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Re: Resolution change
« Reply #3 on: June 30, 2009, 09:25:32 AM »
As I mask the EXIF data I understand the preference is lost and I assume that it then goes to a default setting of 72ppi.

If this is what happens is it possible for me to change the default setting to 300ppi?


Not without unmasking the EXIF data first.

-Kirk

Offline Roger Caris

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Re: Resolution change
« Reply #4 on: July 01, 2009, 02:12:16 AM »
Kirk
As will be obvious from my questions and replies I am not a computer person. So I dont understand why the ppi changes from 300 to 72 when I mask the EXIF data.

Could you tell me how to mask the EXIF data and keep the resolution at 300.

Roger

Offline Kirk Baker

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Re: Resolution change
« Reply #5 on: July 01, 2009, 06:36:02 AM »
Roger,

As will be obvious from my questions and replies I am not a computer person. So I dont understand why the ppi changes from 300 to 72 when I mask the EXIF data.

Could you tell me how to mask the EXIF data and keep the resolution at 300.

It's just not possible.  The only place that the DPI information is stored is in the EXIF data.  If you mask the EXIF data (which means that to all applications that the EXIF data is missing) then each application will use its own default value for various EXIF data.  One application may decide that the default is 72, another may decide that the default is 96, and so on.

You can't mask the EXIF data and also have parts of it be visible.  It may be better if you tell me what effect you're trying to achieve?

-Kirk

Offline Roger Caris

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Re: Resolution change
« Reply #6 on: July 01, 2009, 08:20:04 AM »
Kirk
I am supplying jpegs on a DVD to my wedding customers. I do not want them to see that they have not got some of the files. I want to supply them at 300 ppi so they can make prints from them.
Roger

Offline Kirk Baker

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Re: Resolution change
« Reply #7 on: July 01, 2009, 10:35:03 AM »
Roger,

I am supplying jpegs on a DVD to my wedding customers. I do not want them to see that they have not got some of the files. I want to supply them at 300 ppi so they can make prints from them.

Most end users don't know a thing about EXIF data.  What in the EXIF data do you think would tip them off?  Why is it a bad thing that they would find out that they didn't get every single photo you took?  (I mean I'm sure you took great photos and all, but not all of them will be winners, right?)

The DPI setting is really just a hint.  Pixels are pixels and the user can print out a 72 DPI image pretty much the same as a 300 DPI image.  The pixel dimensions of the image are completely unaffected by the DPI setting.  The megapixel count doesn't change with the DPI.

-Kirk

Offline Hayo Baan

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Re: Resolution change
« Reply #8 on: July 01, 2009, 01:37:53 PM »
The DPI setting is really just a hint.  Pixels are pixels and the user can print out a 72 DPI image pretty much the same as a 300 DPI image.  The pixel dimensions of the image are completely unaffected by the DPI setting.  The megapixel count doesn't change with the DPI.

Unrelated to this post, but thank you Kirk for wording this so eloquently!

Rant On
Even at my school (I study photographic design) people still do not seem to always understand this and will say things like "you have to set dpi to 72 for web" for instance. Completely ignoring the fact that it's the pixels that count, not the ppi (oh, and we won't go into the dpi vs ppi discussion either, now shall we?)
Rant off

Sorry about that one, just had to get this off my chest!  ;D

Cheers
Hayo Baan - Photography
Web: www.hayobaan.nl

Offline Roger Caris

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Re: Resolution change
« Reply #9 on: July 02, 2009, 07:47:35 AM »
Kirk
I assumed my customers would be able to deduce that files were missing.

Situations can occur that you miss out a shot where the subject blinks or a person has looked away. So shots like this are missed out. Very often you can take a 1000 pictures at a wedding and cull them down to 400 keepers. If the bride and groom realise that a lot are not there they will ask to see them all. This would then not be a pleasant set of previews to look at.

It would be like a tailor pinning his offcuts on to the suit he has just made and showing that to his customer.

Roger

Offline Kirk Baker

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Re: Resolution change
« Reply #10 on: July 02, 2009, 08:26:44 AM »
Roger,

I assumed my customers would be able to deduce that files were missing.

Situations can occur that you miss out a shot where the subject blinks or a person has looked away. So shots like this are missed out. Very often you can take a 1000 pictures at a wedding and cull them down to 400 keepers. If the bride and groom realise that a lot are not there they will ask to see them all. This would then not be a pleasant set of previews to look at.

It would be like a tailor pinning his offcuts on to the suit he has just made and showing that to his customer.

I'd say that if you were to rename your photos (the keepers only) with the customer's name (or some other identifying label) and then use the {sequence} variable to name them sequentially, then no one would be able to tell that you shot nothing less than 100% keepers.  No need to mask out EXIF data.

-Kirk