Re: BabelColor PatchTool
Re: BabelColor PatchTool
- Subject: Re: BabelColor PatchTool
- From: Ken Fleisher <email@hidden>
- Date: Tue, 26 Aug 2014 07:40:10 -0400
Thank you for the explanation. I thought I was clipping the data to my
monitor's gamut, but I see now that I did this incorrectly. I will try it
again today following your steps. Thanks!
Steve, I appreciate the reply, but your explanation is not entirely
correct. Some monitors, such as the Eizo, don't just set brightness and
gain values. The LUTs are actually uploaded and stored in the monitor
instead of the video card. This allows the LUT to be greater than 8-bit
encoding (usually 12-14 bit) which gives greater granularity and the
ability to hold more shadow detail, for example. It is because of this
feature of my monitors that I was not certain how the various tools in
PatchTool were handling the interpretation of the ICC profile, which
contains some, but not all, of the profiling data.
Ken
On Mon, Aug 25, 2014 at 6:23 PM, dpascale <email@hidden> wrote:
> Ken, I did not realize at first that you sent the question to the
> ColorSync list and answered directly to you, here is the answer to the list.
> (but we can continue off-list of course)
>
> Danny
>
>
>
> --------------------------------------------
>
> Ken,
>
> "So if I convert the patches to the monitor profile, this should bring the
> colors into the monitors gamut? "
>
> Yes and No! Let's see
>
> What is your procedure to:
> 1- Generate the original patch list?
> 2- Convert to profile? (I presume using Gamut Tool: Data sent to PCS
> (buttons on the right side), destination profile: monitor; if not please
> detail)
>
> IMPORTANT: When converting to an RGB Destination profile, the output will
> be properly computed but will not be clipped in RGB. However, you will get
> max R, G, or B values over 255 and below zero instead of clipping. These
> are computed as per the extended sRGB standard and prevent clipping for the
> apps that manage it (and will be clipped for those who dont). So if you use
> the file as input in PatchTool, it will be seen as the same as your
> original patch list (because PatchTool will properly convert the values
> higher than 255 and lower than zero to the proper XYZ values). To get
> clipped RGB, you need to use Gamut Tool/Clip check(Data sent to PCS), and
> manually extract the RGB list from the exported Compare file with a
> spreadsheet. (I guess I should add an option to perform a "hard" clip on
> the data for those type of applications!).
>
>
> "..but the Display Check wouldn't let me use the same profile as source
> and destination"
>
> This is equivalent to no color management, and I understand this is what
> you want.
> The fact that you cannot select the source profile is not an issue since,
> when you import these patches, they should be assigned to the proper
> monitor profile (in the Tabular data tab), and the computed XYZ data should
> be correct.
> It is as if the first part of the transform, from RGB to PCS is already
> done, and the second part part, from PCS to display will be done during the
> check. However, because of how PatchTool exports and imports RGB, you need
> hard clipped data, as we discussed above.
>
> You can send me some files if it can help the discussion,
>
> Danny
>
> ----- Original Message ----- From: Ken Fleisher
> To: dpascale
> Sent: Monday, August 25, 2014 4:16 PM
> Subject: Re: BabelColor PatchTool
>
>
> Thanks Danny. Of course, I read your quote in the manual and I understand
> all that. The monitor is correctly calibrated and set up. I just wasn't
> sure how the software was handling the gamut stuff since the LUTs are only
> in the monitor. So if I convert the patches to the monitor profile, this
> should bring the colors into the monitors gamut? I tried to do that and
> then use those patches as the target for Display Check (so that my results
> are not influenced by out of gamut colors), but the Display Check wouldn't
> let me use the same profile as source and destination.
>
> Anyhow, thanks for your reply. You have verified that I did my testing
> correctly.
>
> Ken
>
>
>
>
> On Mon, Aug 25, 2014 at 4:02 PM, dpascale <email@hidden>
> wrote:
>
> Hello Ken,
>
> --------------
> PatchTool Help 4.6, p 97:
> Important: PatchTool will NOT load the graphics card or monitor LUTs
> corresponding to a selected destination profile. Make sure the LUTs
> corresponding to the selected profile are loaded and that the display
> settings (R, G, and B channels and the display brightness) are appropriate
> for this profile. In particular, for Windows computers, the LUTs are NOT
> updated when the display profile is changed using the display properties
> dialog. A dedicated LUT loading application, or a reboot, is required.
> --------------
>
> Usually, on a Mac, the LUT are loaded when changing the profile. For
> specialized displays which have additional internal LUTs, such as Eizo and
> NEC, there are dedicated manufacturer apps (usually installed as an
> automatic service) that load the proper LUTs when changing the profile.
>
> For any application using the monitor, the only info required (and
> available), is the profile, so if the selected ClipCheck profile
> corresponds to the monitor profile, and if that profile was properly
> assigned, you are OK.
>
> Danny
>
>
> ----- Original Message ----- From: "Ken Fleisher" <email@hidden>
> To: "ColorSync Users Mailing List" <email@hidden>
> Sent: Monday, August 25, 2014 3:28 PM
> Subject: BabelColor PatchTool
>
>
>
> When using BabelColor PatchTool for evaluating profile gamut and
> monitor
> performance, what exactly is happening when you are using a monitor
> such as
> an Eizo where the LUTs are uploaded to the monitor?
>
> If I use the Gamut Tools and Display Check, I need to select the
> destination profile. When I select the monitor's profiles (created
> with
> basICColor Display 5), of course the profile does not actually
> contain the
> LUTs. So how accurate is the Clip Check in Gamut Tools and the various
> stats that result from a Gamut Check? Is there some other method for
> testing these monitors performance when the profile does not contain
> all of
> the necessary information?
>
> Thanks.
> Ken
>
>
> ----- Original Message ----- From: "Ken Fleisher" <email@hidden>
> To: "ColorSync Users Mailing List" <email@hidden>
> Sent: Monday, August 25, 2014 3:28 PM
> Subject: BabelColor PatchTool
>
>
> When using BabelColor PatchTool for evaluating profile gamut and monitor
>> performance, what exactly is happening when you are using a monitor such
>> as
>> an Eizo where the LUTs are uploaded to the monitor?
>>
>> If I use the Gamut Tools and Display Check, I need to select the
>> destination profile. When I select the monitor's profiles (created with
>> basICColor Display 5), of course the profile does not actually contain the
>> LUTs. So how accurate is the Clip Check in Gamut Tools and the various
>> stats that result from a Gamut Check? Is there some other method for
>> testing these monitors performance when the profile does not contain all
>> of
>> the necessary information?
>>
>> Thanks.
>> Ken
>> _______________________________________________
>>
>
>
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