Re: Question about tone remapping with Relative Colorimetric Rendering
Re: Question about tone remapping with Relative Colorimetric Rendering
- Subject: Re: Question about tone remapping with Relative Colorimetric Rendering
- From: Scott Martin <email@hidden>
- Date: Sat, 01 Jun 2013 09:42:26 -0500
What are your conversation options set to in the color settings? AbsCol?
Oh, can you repeat all of this without using the word "accurate"? :-)
Scott Martin
On Jun 1, 2013, at 9:35 AM, Louis Dina <email@hidden> wrote:
> I'm trying to understand how tones are remapped when going from file to
> print, using an RGB driver. I'll use an example so my question is clear.
>
> I created a black to white gradient in Photoshop, Adobe RGB. 11 step
> posterization. I purposely chose to keep color out of this test, since I
> wanted to keep it simple to understand how the luminance values get
> mapped. That gives RGB numbers, from dark to light, of 0 25 51 76 102 128
> 153 178 204 229 255. The info palette shows L* values of 0 6 20 32 43 54 64
> 73 83 91 100.
>
> I *converted* the file to a custom RGB profile (using the epson printer
> driver), Relative Colorimetric, BPC on, of a weak Dmax matte fine art
> paper. This paper achieves about 18L* for Dmax and has a white of about
> 96L*. I chose a weak paper on purpose to amplify the effect.
>
> The info palette shows changes in the two darkest patches ONLY. Black goes
> from L* of 0 to 2, and the next lighter patch goes from 6 to 8. All other
> patches remain the same. The RGB numbers change too reflecting profile
> tables to adjust brightness and neutrality. I believe these are the new RGB
> numbers that will be sent to the printer driver, correct? They obviously
> aren't the achieved values in the print, because the paper can achieve only
> 18L* black and 96L* white.
>
> Is there a way to know what the final L* values in the print will be using
> Photoshop, or in looking at the profile? If so, how? I assume this
> information must be in the profile. (I built this printer profile using
> i1Profiler).
>
> OK, switch to the original RGB numbers (before conversion) and go to Proof
> Preview instead of Convert to Profile. If I proof preview using RC intent,
> BPC turned On, the file display shows the two darkest patches brightening
> up (same as the conversion). However, since I am not converting, the
> numbers in the info palette are the original numbers.
>
> Still in Proof Preview, RC, BPC On, if I turn on Simulate Black Ink, the
> entire tonal scale lightens up, most notably, from blacks to the midtones,
> but even a little bit in the 1/4 tones. Obviously, the profile knows this,
> but it doesn't show me the numbers.
>
> If I then turn on Simulate Paper White, the display reflects the dingy
> yellow-white of the paper (96L/0a/3b or so). Now, the light end of the
> tonal scale is scaled back, giving a more accurate view of the real tonal
> range of the final print. Unfortunately, the numbers in the info palette
> still show the original numbers. Is there a way to see the final numbers I
> would read in the print if using a spectro (assuming a perfect profile, of
> course)?
>
> Sorry for the long email, but I want it to be clear. RC Intent has always
> been described as accurately reproducing in-gamut colors, then clipping all
> out-of-gamut colors and tones, bringing them back to the edge of the
> destination gamut. Obviously, the whitest white this paper can produce is
> 96L/0a/3b, and the blackest black is 18L*/0a/0b.
>
> Here's the real question...Will all the grayscale tones in my step wedge
> from 18L to 96L reproduce accurately on the final paper using RC Intent? Or
> will they be scaled somehow? The Proof Preview shows them ALL changing.
>
> And will my two black patches (original numbers of 0L and 6L) both end up
> being 18L? Again, the proof preview says No. I'd like to believe the
> midtones will stay locked, so 50L in my info palette will read 50L in the
> print, but I am not convinced this is the case.
>
> Thanks for any responses, and sorry again about the length of this email. I
> hope it was clear.
>
> Lou Dina
> _______________________________________________
> Do not post admin requests to the list. They will be ignored.
> Colorsync-users mailing list (email@hidden)
> Help/Unsubscribe/Update your Subscription:
>
> This email sent to email@hidden
_______________________________________________
Do not post admin requests to the list. They will be ignored.
Colorsync-users mailing list (email@hidden)
Help/Unsubscribe/Update your Subscription:
This email sent to email@hidden