RE: Linear Tonal Response output (print) ICC profiles possible?
I still have a couple of BabelColor White references. Nothing comes close to their usefulness -- and prices. Almost L*100. Best / Roger -----Original Message----- From: colorsync-users [mailto:colorsync-users-bounces+graxx=videotron.ca@lists.apple.com] On Behalf Of Ernst Dinkla Sent: Saturday, January 6, 2018 6:39 AM To: Ben Goren <ben@trumpetpower.com> Cc: 'colorsync-users?lists.apple.com' List <colorsync-users@lists.apple.com> Subject: Re: Linear Tonal Response output (print) ICC profiles possible? On Fri, Jan 5, 2018 at 10:32 PM, Ben Goren <ben@trumpetpower.com> wrote:
On Jan 5, 2018, at 1:52 PM, forums@walkerblackwell.com wrote:
All other things can go where they go for now. If the print is near the sun I’m fine with it blinding me, if the print is in shadow I’m fine with it looking too dark. But linear printed L* values (percentage of reflected light) related to a TILE WHITE of a spectro is what I’m after.
First...it's really important to understand that L* values are _not_ the percentage of reflected light. L* values (ideally but not actually) represent 100 perceptually-equal step wedges between absolute black (*NOT* dMax, but an actual absence of light) and a perfect lambertian reflector (of which, again, PTFE thread tape is an astonishingly good approximation) under close-to-typical illumination.
You're familiar, I hope, with the famous Kodak 18% gray card? It reflects (within manufacturing tolerances, which are pretty broad) 18% of incident light.
Plop your spectrometer on it, and it'll give you a D50 Lab reading of L*=50, a*=0, b*=0...plus or minus at least five units (did I mention manufacturing tolerances?).
Meanwhile there are some OBA free inkjet papers, satin finish, that come close to the white reflectance of PTFE thread tape (12mm wide, 9mm high stack, Lab 98.9 0.0 0.5) Lab 98.8 0.0 0.9 for Arca Proline Vibrant Superior FineArt Rag satin 300 gsm, Lab 98.8 -0.2 1.8 for Inkpress Baryta 307 gsm. White museum board underneath the samples. Over the last decade there has been quite a gain in paper white reflectance of inkjet papers without using OBA whitening agents. For the dynamic range (in practice) it actually is more important than Dmax improvements. OBA free papers improve much to better color constancy in changing light conditions. For inkjet inks the HP Z models have a Photo Black for gloss papers that is near neutral, the same for the grey inks in some of the Z models. Fading to a warmer black in time is minimal. The Matte Black ink is right away warmer though. Of the plain carbon pigment based matte black inks the latest version of the Eboni black inks (MIS) is the most neutral but like all carbon pigments a bit warm. That said for most humans neutral is still warm, one wonders what that respons would have been if OBA never had been used in any product. Pity that there is no PTFE thread tape in a grey quality that is as inexpensive, neutral and fade resistant as the white version. As a white reference / gray card the PTFE thread tape has limited use being near Lab 100. I went through several grey plastic samples to find near neutral ones for that purpose, they exist with numbers not beyond Delta E* 0.8 from neutral and are less prone to shift in time due to filth or fading than the normal grey cards. Various inexpensive products intended to be neutrally colored are made in higher quantities and more batches than the special tiles (ceramic, BaSO4, PTFE) for optical measurements, the deviations will be higher but a nice (not UV cut) spectrometer can be a godsend then. Met vriendelijke groet, Ernst http://www.pigment-print.com/spectralplots/spectrumviz_1.htm July 2016 update, 700+ inkjet media white spectral plots _______________________________________________ Do not post admin requests to the list. They will be ignored. colorsync-users mailing list (colorsync-users@lists.apple.com) Help/Unsubscribe/Update your Subscription: https://lists.apple.com/mailman/options/colorsync-users/graxx%40videotron.ca This email sent to graxx@videotron.ca
Hello Roger, " BabelColor White references ": They stopped being sold/offered in 2012. Time flies... Danny www.babelcolor.com -----Message d'origine----- De : colorsync-users [mailto:colorsync-users-bounces+dpascale=babelcolor.com@lists.apple.com] De la part de Roger Breton Envoyé : 6 janvier 2018 13:11 À : 'Ernst Dinkla'; 'Ben Goren' Cc : ''colorsync-users?lists.apple.com' List' Objet : RE: Linear Tonal Response output (print) ICC profiles possible? I still have a couple of BabelColor White references. Nothing comes close to their usefulness -- and prices. Almost L*100. Best / Roger -----Original Message----- From: colorsync-users [mailto:colorsync-users-bounces+graxx=videotron.ca@lists.apple.com] On Behalf Of Ernst Dinkla Sent: Saturday, January 6, 2018 6:39 AM To: Ben Goren <ben@trumpetpower.com> Cc: 'colorsync-users?lists.apple.com' List <colorsync-users@lists.apple.com> Subject: Re: Linear Tonal Response output (print) ICC profiles possible? On Fri, Jan 5, 2018 at 10:32 PM, Ben Goren <ben@trumpetpower.com> wrote:
On Jan 5, 2018, at 1:52 PM, forums@walkerblackwell.com wrote:
All other things can go where they go for now. If the print is near the sun I’m fine with it blinding me, if the print is in shadow I’m fine with it looking too dark. But linear printed L* values (percentage of reflected light) related to a TILE WHITE of a spectro is what I’m after.
First...it's really important to understand that L* values are _not_ the percentage of reflected light. L* values (ideally but not actually) represent 100 perceptually-equal step wedges between absolute black (*NOT* dMax, but an actual absence of light) and a perfect lambertian reflector (of which, again, PTFE thread tape is an astonishingly good approximation) under close-to-typical illumination.
You're familiar, I hope, with the famous Kodak 18% gray card? It reflects (within manufacturing tolerances, which are pretty broad) 18% of incident light.
Plop your spectrometer on it, and it'll give you a D50 Lab reading of L*=50, a*=0, b*=0...plus or minus at least five units (did I mention manufacturing tolerances?).
Meanwhile there are some OBA free inkjet papers, satin finish, that come close to the white reflectance of PTFE thread tape (12mm wide, 9mm high stack, Lab 98.9 0.0 0.5) Lab 98.8 0.0 0.9 for Arca Proline Vibrant Superior FineArt Rag satin 300 gsm, Lab 98.8 -0.2 1.8 for Inkpress Baryta 307 gsm. White museum board underneath the samples. Over the last decade there has been quite a gain in paper white reflectance of inkjet papers without using OBA whitening agents. For the dynamic range (in practice) it actually is more important than Dmax improvements. OBA free papers improve much to better color constancy in changing light conditions. For inkjet inks the HP Z models have a Photo Black for gloss papers that is near neutral, the same for the grey inks in some of the Z models. Fading to a warmer black in time is minimal. The Matte Black ink is right away warmer though. Of the plain carbon pigment based matte black inks the latest version of the Eboni black inks (MIS) is the most neutral but like all carbon pigments a bit warm. That said for most humans neutral is still warm, one wonders what that respons would have been if OBA never had been used in any product. Pity that there is no PTFE thread tape in a grey quality that is as inexpensive, neutral and fade resistant as the white version. As a white reference / gray card the PTFE thread tape has limited use being near Lab 100. I went through several grey plastic samples to find near neutral ones for that purpose, they exist with numbers not beyond Delta E* 0.8 from neutral and are less prone to shift in time due to filth or fading than the normal grey cards. Various inexpensive products intended to be neutrally colored are made in higher quantities and more batches than the special tiles (ceramic, BaSO4, PTFE) for optical measurements, the deviations will be higher but a nice (not UV cut) spectrometer can be a godsend then. Met vriendelijke groet, Ernst http://www.pigment-print.com/spectralplots/spectrumviz_1.htm July 2016 update, 700+ inkjet media white spectral plots _______________________________________________ Do not post admin requests to the list. They will be ignored. colorsync-users mailing list (colorsync-users@lists.apple.com) Help/Unsubscribe/Update your Subscription: https://lists.apple.com/mailman/options/colorsync-users/graxx%40videotron.ca
participants (2)
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dpascale
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Roger Breton