Re: Color Management for iPad?
Re: Color Management for iPad?
- Subject: Re: Color Management for iPad?
- From: Tom Lianza <email@hidden>
- Date: Mon, 01 Aug 2011 11:52:14 -0400
- Thread-topic: Color Management for iPad?
Hello Jan-Peter
>
> Especially in the tablet market, we have a growing group of professional
> users like e.g. photographers, people in medical imaging, graphic
> designers doing presentations at customer sides....
>
Wouldn't it make the most sense to optimize the image for the platform used
for presentation? In this sense, the tablet is just like a printer, it can
be characterized, profiled, and images can be rendered for it directly. You
don't need any active color management on the tablet for those tasks.
> If the App for creating and configuring an individual display
> ICC-profile is certified e.g. through Apple and available through the
> iTunes Store, I don´t see any security issues.
> If people in the professional imaging area already have an instrument
> and software for profiling their desktop environment, they probably
> would buy an App to profile their iPad, if they have the need for
> accurate colors.
>
I wasn't clear, it's not the profile of the device display, it's the
millions of arbitrary profiles that can be attached to the billions of
images in the digital domain. This is where the security issue is. That is
a digital backdoor that is not easy to certify. Another point is where do
you draw the line, are cmyk images OK, how about LAB encodings, why not
establish DNG as a web standard?
> If an mobile device with hardcoded "sRGB-to-display-transformation"
> ignores an embedded AdobeRGB profile in images, we have a very strange
> form of gamut mapping. At least such images should be rendered from
> AdobeRGB to sRGB before rendered to the display.
>
You would also have very strange gamut mapping if you did this in an
application as well. Where would you suggest that transformation happens.
Even on the desktop, there are many applications which would simply fail if
that is what you want. Mapping from a larger gamut to a smaller gamut
always involves compromises. The question a photographer needs to answer
is:" Do I want to detect the artifact before I ship the image off to the
customer, or should I just assume he won't notice when his on board color
management system has bad side effects due to gamut compression?"
Regards,
Tom
On 8/1/11 10:18 AM, "Jan-Peter Homann" <email@hidden> wrote:
> Hello Tom and all
> Some comments in the text:
>
> Am 01.08.11 15:25, schrieb Tom Lianza:
>> 1. The mobile network providers don't want to see a lot of images on the
>> network. They use bandwidth (which you are paying for) and it can have a
>> real impact on through put in crowded urban networks. Mobile providers,
>> especially in the US, would rather not have to deal with the issues images
>> at all.
> Mobile devices today have access both to the mobile network and to W-Lan
> networks. They have integrated cameras and provide applications like
> e.g. image and PDF viewers, where the users expects support for
> ICC-profiles in images, pdf files and other data.
>
> Especially in the tablet market, we have a growing group of professional
> users like e.g. photographers, people in medical imaging, graphic
> designers doing presentations at customer sides....
>
>
>>
>> 2.ICC profiles are effectively user-supplied, binary, meta data which is an
>> absolute negative security issue on a mobile network. The reason that phone
>> applications are so carefully screened and the development environments are
>> so tightly bound to the OS is the fundamental security issue. An
>> application CANNOT BE ALLOWED to bring down a phone, hence they will be
>> restricted to very carefully controlled application memory space. I
>> seriously doubt that user supplied profiles will ever be used at the highest
>> level in a mobile device. At best, it will be application based. An app on
>> a phone is far more restricted than an application on the desktop. The
>> browser issue is more complex because it should run seamlessly in both
>> worlds.
> Firstly, the device itself should be delivered with a cannend display
> ICC-profile and the OS should deliver a framework, that Apps can use the
> canned display ICC-profile. The current problem is, that such basic
> things are not available for iOS and Android.
>
> If the App for creating and configuring an individual display
> ICC-profile is certified e.g. through Apple and available through the
> iTunes Store, I don´t see any security issues.
> If people in the professional imaging area already have an instrument
> and software for profiling their desktop environment, they probably
> would buy an App to profile their iPad, if they have the need for
> accurate colors.
>
>> 3. For traditional color management to work, there must be a source and a
>> destination defined BEFORE RENDERING. The question of untagged (source
>> unknown) has generally been defined to be sRGB. If that assumption is
>> followed in the system, a very good rendering of sRGB to display can be done
>> with a relatively simple transformation. The fact is that nearly all mobile
>> devices do this in the hardware pipeline. The need to accommodate a wide
>> range of display technologies is well understood and graphics engine
>> designers have various color correction hardware built into the chip. From
>> the standpoint of the mobile designer, they already have done "color
>> management" and the fact that you can't see it or change it is of no
>> consequence to them. If you render the image to sRGB, leave it untagged,
>> there will be no major surprises, unless something stupid happens in the
>> upload process.
>
> What about digital images having AdobeRGB embedded and shared between
> desktop, mobile device and the cloud ?
>
>> 4. I cannot understand how a photographer would allow some alien device,
>> with unknown rendering characteristics, perform color management on the
>> image. Given that the trend is towards lower gamut, high luminance
>> displays, it is very likely that the output after late binding color
>> management will clip, in relative colorimetric mode. If the manufacturer
>> decides on a perceptual rendering, then the color you see will be very much
>> determined by the taste of the platform vendor, not you the photographer.
>> In any instance, the result that the end user sees, will not be the image
>> the photographer saw.
> If an mobile device with hardcoded "sRGB-to-display-transformation"
> ignores an embedded AdobeRGB profile in images, we have a very strange
> form of gamut mapping. At least such images should be rendered from
> AdobeRGB to sRGB before rendered to the display.
>
> Jan-Peter
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