Re: [Lcms-user] Precision loss in floating point transform

2013-11-24 Thread Graeme Gill
Anders Torger wrote: > Ok, I was afraid that this would be the response. People are using > legacy icc profiles all the time so having poor support for them is not > really a great idea, at least not for our project. As a first step we > can implement matrix shaper conversions ourselves though a

Re: [Lcms-user] Precision loss in floating point transform

2013-11-24 Thread Anders Torger
Thanks for the help! Yes it's mostly like the old sRGB and that. Did not know about those tricks, understand it's more important to protect compatbility. I'll certainly look into the plugin thing. /Anders On 11/24/2013 06:24:18 PM, marti.ma...@littlecms.com wrote: > > Anders, > > This is not

Re: [Lcms-user] Precision loss in floating point transform

2013-11-24 Thread marti . maria
Anders, This is not a matter of adding or not the feature. It would be easy for me just to promote the tables and use them in floating point mode. The issue is, there are profiles around using the limited precision as a trick to do other things, and doing what you propose would break color rendit

Re: [Lcms-user] Precision loss in floating point transform

2013-11-24 Thread Anders Torger
Ok, I was afraid that this would be the response. People are using legacy icc profiles all the time so having poor support for them is not really a great idea, at least not for our project. As a first step we can implement matrix shaper conversions ourselves though as it's quite easy to do, bu

Re: [Lcms-user] Precision loss in floating point transform

2013-11-23 Thread marti . maria
Quoting Anders Torger : Hello, > with the gamma curve specified as an array of numbers That's the whole point. If the gamma is specified as an array of 16 bits numbers, then the interpolation happens in 16 bits. This is because the profile, not the CMM. In fact, if the profile uses multi

[Lcms-user] Precision loss in floating point transform

2013-11-23 Thread Anders Torger
Hello, I'm one of the developers of RawTherapee, a photo editing software with a floating point engine and which uses lcms2 for color management. Recently I discovered that when making a transform from float to float (or float to 16 bit) using a basic icc with the gamma curve secified as an a