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UT2 1280 Curves/Paul Roark

UT2 1280 Curves/Paul Roark

2004-02-29 by rbehr2001

Paul,
Page 6 of your http://home1.gte.net/res09aij/UT2-Readme.htm indicates 
that the red and green curves have only 3 internal points on them. 
But the curves I've used (Prem Semi Gloss for Eboni & Photo Black) 
have many points on them. Am I missing something?

Thanks, 
Bob

RE: [Digital BW] UT2 1280 Curves/Paul Roark

2004-02-29 by Paul Roark

Bob,

So true.  EEM was the first one I did, and it didn't need any other points
on the main curves, as I recall.  Subsequently I found the shadows below 75%
often needed some points.  I should modify the Readme to reflect this.

What I've tried to do is hold the points down in the midtones, which is
where the tones show the most.  The idea is to make it easy for everyone to
slightly modify the curves/tones by making offsetting moves of the red and
green points.  In the shadows where there are points on some curves, this
works to a certain extent also, and visual inspection of a 21-step file
print will, I think, be easy enough to get those areas under control.

Paul
www.PaulRoark.com 

For UT2 information, curves, and settings see:
http://home1.gte.net/res09aij/
____________________
Show quoted textHide quoted text
-----Original Message-----
From: rbehr2001 [mailto:rsbehr@...] 
Sent: Sunday, February 29, 2004 9:55 AM
To: DigitalBlackandWhiteThePrint@yahoogroups.com
Subject: [Digital BW] UT2 1280 Curves/Paul Roark

Paul,
Page 6 of your http://home1.gte.net/res09aij/UT2-Readme.htm indicates 
that the red and green curves have only 3 internal points on them. 
But the curves I've used (Prem Semi Gloss for Eboni & Photo Black) 
have many points on them. Am I missing something?

Thanks, 
Bob




Please visit the Group Homepage to check the Files, and other resources as
they are often being updated.

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guidelines, and to abide by the actions and decisions of the group Owner and
Moderators. See "Group Topic, Rules and Guidelines" in the Files section:
http://groups.yahoo.com/group/DigitalBlackandWhiteThePrint/files/

BY PARTICIPATING IN AND/OR POSTING MESSAGES TO THE DIGITAL BW, THE PRINT
YAHOO! GROUP YOU EXPRESSLY UNDERSTAND AND AGREE THAT THE "OWNER" AND
"MODERATORS" OF DIGITAL BW, THE PRINT YAHOO GROUP SHALL NOT BE LIABLE TO YOU
FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, CONSEQUENTIAL OR EXEMPLARY
DAMAGES, INCLUDING BUT NOT LIMITED TO, DAMAGES FOR LOSS OF PROFITS,
GOODWILL, USE, DATA OR OTHER INTANGIBLE LOSSES (EVEN IF THE  "OWNER" AND
"MODERATORS" OF DIGITAL BW, THE PRINT YAHOO GROUP HAVE BEEN ADVISED OF THE
POSSIBILITY OF SUCH DAMAGES), RESULTING FROM: (i) THE USE OR THE INABILITY
TO USE THE DIGITAL BW, THE PRINT YAHOO GROUP; (ii) UNAUTHORIZED ACCESS TO OR
ALTERATION OF YOUR TRANSMISSIONS OR DATA; (iii) STATEMENTS OR CONDUCT OF ANY
THIRD PARTY ON THE DIGITAL BW, THE PRINT YAHOO GROUP; OR (iv) ANY OTHER
MATTER RELATING TO THE DIGITAL BW, THE PRINT YAHOO GROUP.
 
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Re: [Digital BW] UT2 1280 Curves/Paul Roark

2004-03-05 by Robert Behr

Paul,

Thanks for the help. I've started working on custom curves. I'm trying to establish what an ideal distribution of values should be. I note that in the Hobeman instructions for "Customizing MIS Ultratone Curves" suggest that Grayvalue percentages (21 step) vs. RGB values (0-255) be in a linear relationship. However, when I measure 21 step grayscales printed on a 2200 (with color ink) and in Piezography, I get significantly different relationship (which is closer to what I get from your curves).

The results are as follows:
Percent                 RGB
      0
     255
     
      5
     250
     
      10
     245
     
      15
     239
     
      20
     233
     
      25
     226
     
      30
     219
     
      35
     212
     
      40
     204
     
      45
     195
     
      50
     185
     
      55
     174
     
      60
     162
     
      65
     149
     
      70
     135
     
      75
     120
     
      80
     104
     
      85
     86
     
      90
     64
     
      95
     35
     
      100
     0
     


What goals are you using?

Thanks,
Bob
Show quoted textHide quoted text
  ----- Original Message ----- 
  From: Paul Roark 
  To: DigitalBlackandWhiteThePrint@yahoogroups.com 
  Sent: Sunday, February 29, 2004 1:37 PM
  Subject: RE: [Digital BW] UT2 1280 Curves/Paul Roark


  Bob,

  So true.  EEM was the first one I did, and it didn't need any other points
  on the main curves, as I recall.  Subsequently I found the shadows below 75%
  often needed some points.  I should modify the Readme to reflect this.

  What I've tried to do is hold the points down in the midtones, which is
  where the tones show the most.  The idea is to make it easy for everyone to
  slightly modify the curves/tones by making offsetting moves of the red and
  green points.  In the shadows where there are points on some curves, this
  works to a certain extent also, and visual inspection of a 21-step file
  print will, I think, be easy enough to get those areas under control.

  Paul
  www.PaulRoark.com 

  For UT2 information, curves, and settings see:
  http://home1.gte.net/res09aij/
  ____________________

  -----Original Message-----
  From: rbehr2001 [mailto:rsbehr@...] 
  Sent: Sunday, February 29, 2004 9:55 AM
  To: DigitalBlackandWhiteThePrint@yahoogroups.com
  Subject: [Digital BW] UT2 1280 Curves/Paul Roark

  Paul,
  Page 6 of your http://home1.gte.net/res09aij/UT2-Readme.htm indicates 
  that the red and green curves have only 3 internal points on them. 
  But the curves I've used (Prem Semi Gloss for Eboni & Photo Black) 
  have many points on them. Am I missing something?

  Thanks, 
  Bob




  Please visit the Group Homepage to check the Files, and other resources as
  they are often being updated.

  http://groups.yahoo.com/group/DigitalBlackandWhiteThePrint

  If you wish to receive no emails or just a daily digest, or you wish to
  unsubscribe, please edit your Membership preferences by visiting this same
  page.

  Please follow these basic guidelines:
  - As threads develop, trim off excess portions of earlier messages to keep
  them short.
  - Good manners are required at all time. No personal attacks or flames.
  Hostile, aggressive or argumentative users may be removed from the
  membership without notice.
  - Keep your posts and threads related to the group topic of digital B&W
  printing. Users who persistently make off-topic posts may be removed from
  the membership.
  - By posting on this forum you agree to abide by the group rules and
  guidelines, and to abide by the actions and decisions of the group Owner and
  Moderators. See "Group Topic, Rules and Guidelines" in the Files section:
  http://groups.yahoo.com/group/DigitalBlackandWhiteThePrint/files/

  BY PARTICIPATING IN AND/OR POSTING MESSAGES TO THE DIGITAL BW, THE PRINT
  YAHOO! GROUP YOU EXPRESSLY UNDERSTAND AND AGREE THAT THE "OWNER" AND
  "MODERATORS" OF DIGITAL BW, THE PRINT YAHOO GROUP SHALL NOT BE LIABLE TO YOU
  FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, CONSEQUENTIAL OR EXEMPLARY
  DAMAGES, INCLUDING BUT NOT LIMITED TO, DAMAGES FOR LOSS OF PROFITS,
  GOODWILL, USE, DATA OR OTHER INTANGIBLE LOSSES (EVEN IF THE  "OWNER" AND
  "MODERATORS" OF DIGITAL BW, THE PRINT YAHOO GROUP HAVE BEEN ADVISED OF THE
  POSSIBILITY OF SUCH DAMAGES), RESULTING FROM: (i) THE USE OR THE INABILITY
  TO USE THE DIGITAL BW, THE PRINT YAHOO GROUP; (ii) UNAUTHORIZED ACCESS TO OR
  ALTERATION OF YOUR TRANSMISSIONS OR DATA; (iii) STATEMENTS OR CONDUCT OF ANY
  THIRD PARTY ON THE DIGITAL BW, THE PRINT YAHOO GROUP; OR (iv) ANY OTHER
  MATTER RELATING TO THE DIGITAL BW, THE PRINT YAHOO GROUP.

  Yahoo! Groups Links







  Please visit the Group Homepage to check the Files, and other resources as they are often being updated.

  http://groups.yahoo.com/group/DigitalBlackandWhiteThePrint

  If you wish to receive no emails or just a daily digest, or you wish to unsubscribe, please edit your Membership preferences by visiting this same page.

  Please follow these basic guidelines:
  - As threads develop, trim off excess portions of earlier messages to keep them short.
  - Good manners are required at all time. No personal attacks or flames. Hostile, aggressive or argumentative users may be removed from the membership without notice.
  - Keep your posts and threads related to the group topic of digital B&W printing. Users who persistently make off-topic posts may be removed from the membership.
  - By posting on this forum you agree to abide by the group rules and guidelines, and to abide by the actions and decisions of the group Owner and Moderators. See "Group Topic, Rules and Guidelines" in the Files section:
  http://groups.yahoo.com/group/DigitalBlackandWhiteThePrint/files/

  BY PARTICIPATING IN AND/OR POSTING MESSAGES TO THE DIGITAL BW, THE PRINT YAHOO! GROUP YOU EXPRESSLY UNDERSTAND AND AGREE THAT THE "OWNER" AND "MODERATORS" OF DIGITAL BW, THE PRINT YAHOO GROUP SHALL NOT BE LIABLE TO YOU FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, CONSEQUENTIAL OR EXEMPLARY DAMAGES, INCLUDING BUT NOT LIMITED TO, DAMAGES FOR LOSS OF PROFITS, GOODWILL, USE, DATA OR OTHER INTANGIBLE LOSSES (EVEN IF THE  "OWNER" AND "MODERATORS" OF DIGITAL BW, THE PRINT YAHOO GROUP HAVE BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES), RESULTING FROM: (i) THE USE OR THE INABILITY TO USE THE DIGITAL BW, THE PRINT YAHOO GROUP; (ii) UNAUTHORIZED ACCESS TO OR ALTERATION OF YOUR TRANSMISSIONS OR DATA; (iii) STATEMENTS OR CONDUCT OF ANY THIRD PARTY ON THE DIGITAL BW, THE PRINT YAHOO GROUP; OR (iv) ANY OTHER MATTER RELATING TO THE DIGITAL BW, THE PRINT YAHOO GROUP.



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[Non-text portions of this message have been removed]

RE: [Digital BW] UT2 1280 Curves/Paul Roark

2004-03-05 by Paul Roark

Bob,

>... I've started working on custom curves. I'm trying to establish what an
>ideal distribution of values should be.

I have never seen a very good explanation of this issue, just factors to
take into consideration.  I've asked in the past, "What is linear?"  I don't
think there is a simple answer.

> I note that in the Hobeman instructions for "Customizing MIS Ultratone
>Curves" suggest that Grayvalue percentages (21 step) vs. RGB values (0-255)
>be in a linear relationship. However, when I measure 21 step grayscales
>printed on a 2200 (with color ink) and in Piezography, I get significantly
>different relationship (which is closer to what I get from your curves).

In general the say the human eye follows the logarithmic scale.  As such the
f-stops and log scales of the densitometers should be close.  However, it is
also the case that our ability to distinguish steps in the darker regions is
less than in the brighter or midtone sections.  

So, if you assume that the dmax on a matte paper is 1.65 and the paper white
is 0.05, 0.80 would be the arithmetic midpoint.  If, however, this is used
at the 50% density, the scale looks dark.  If I use a log scale that goes
from 0.05 to 1.65, measure the distance between the ends and divide it in
half, the midpoint on the scale is just below 0.30 -- too light (but close
to where some old Epson's put the BO midpoint).

(I'm sure some with a strong math background could do a better job here than
I, but I also think a background in the human visual system is needed --
another field I'm not formally trained in.)

What I did was work from a pragmatic perspective.  I was using the PiezoBW
system.  I wanted my files to be printable and the images to be consistent
with both systems.  So, I took a number of PiezoBW 21-step test strips and
averaged them.  The average for 50% was 0.61.  Smoothing the curves gave me
a 25% of 0.29 and the 75% of 1.03.

At the dark end, the dmax is a critical factor that needs to be considered
for, especially, what is between about 70% and 100%.  To give an idea of
what I've used just based on visual impression, for a dmax of 1.68 I use
1.53 for 95%.  If the dmax is 2.40 (like some glossy papers) I use 1.95 as
the 95% point.  The eye really has trouble seeing into those very dark
blacks in any kind of "normal" light level.  To be really consistent, I
suppose I would have to determine what that "normal" light level is.  As a
practical matter, I make judgments based on how things look in my office.

Hope this helps.

Paul
www.PaulRoark.com

Re: [Digital BW] UT2 1280 Curves/Paul Roark

2004-03-06 by Robert Behr

Paul,

Helps very much. 

Thanks
Show quoted textHide quoted text
  ----- Original Message ----- 
  From: Paul Roark 
  To: DigitalBlackandWhiteThePrint@yahoogroups.com 
  Sent: Friday, March 05, 2004 6:45 PM
  Subject: RE: [Digital BW] UT2 1280 Curves/Paul Roark


  Bob,

  >... I've started working on custom curves. I'm trying to establish what an
  >ideal distribution of values should be.

  I have never seen a very good explanation of this issue, just factors to
  take into consideration.  I've asked in the past, "What is linear?"  I don't
  think there is a simple answer.

  > I note that in the Hobeman instructions for "Customizing MIS Ultratone
  >Curves" suggest that Grayvalue percentages (21 step) vs. RGB values (0-255)
  >be in a linear relationship. However, when I measure 21 step grayscales
  >printed on a 2200 (with color ink) and in Piezography, I get significantly
  >different relationship (which is closer to what I get from your curves).

  In general the say the human eye follows the logarithmic scale.  As such the
  f-stops and log scales of the densitometers should be close.  However, it is
  also the case that our ability to distinguish steps in the darker regions is
  less than in the brighter or midtone sections.  

  So, if you assume that the dmax on a matte paper is 1.65 and the paper white
  is 0.05, 0.80 would be the arithmetic midpoint.  If, however, this is used
  at the 50% density, the scale looks dark.  If I use a log scale that goes
  from 0.05 to 1.65, measure the distance between the ends and divide it in
  half, the midpoint on the scale is just below 0.30 -- too light (but close
  to where some old Epson's put the BO midpoint).

  (I'm sure some with a strong math background could do a better job here than
  I, but I also think a background in the human visual system is needed --
  another field I'm not formally trained in.)

  What I did was work from a pragmatic perspective.  I was using the PiezoBW
  system.  I wanted my files to be printable and the images to be consistent
  with both systems.  So, I took a number of PiezoBW 21-step test strips and
  averaged them.  The average for 50% was 0.61.  Smoothing the curves gave me
  a 25% of 0.29 and the 75% of 1.03.

  At the dark end, the dmax is a critical factor that needs to be considered
  for, especially, what is between about 70% and 100%.  To give an idea of
  what I've used just based on visual impression, for a dmax of 1.68 I use
  1.53 for 95%.  If the dmax is 2.40 (like some glossy papers) I use 1.95 as
  the 95% point.  The eye really has trouble seeing into those very dark
  blacks in any kind of "normal" light level.  To be really consistent, I
  suppose I would have to determine what that "normal" light level is.  As a
  practical matter, I make judgments based on how things look in my office.

  Hope this helps.

  Paul
  www.PaulRoark.com 



  Please visit the Group Homepage to check the Files, and other resources as they are often being updated.

  http://groups.yahoo.com/group/DigitalBlackandWhiteThePrint

  If you wish to receive no emails or just a daily digest, or you wish to unsubscribe, please edit your Membership preferences by visiting this same page.

  Please follow these basic guidelines:
  - As threads develop, trim off excess portions of earlier messages to keep them short.
  - Good manners are required at all time. No personal attacks or flames. Hostile, aggressive or argumentative users may be removed from the membership without notice.
  - Keep your posts and threads related to the group topic of digital B&W printing. Users who persistently make off-topic posts may be removed from the membership.
  - By posting on this forum you agree to abide by the group rules and guidelines, and to abide by the actions and decisions of the group Owner and Moderators. See "Group Topic, Rules and Guidelines" in the Files section:
  http://groups.yahoo.com/group/DigitalBlackandWhiteThePrint/files/

  BY PARTICIPATING IN AND/OR POSTING MESSAGES TO THE DIGITAL BW, THE PRINT YAHOO! GROUP YOU EXPRESSLY UNDERSTAND AND AGREE THAT THE "OWNER" AND "MODERATORS" OF DIGITAL BW, THE PRINT YAHOO GROUP SHALL NOT BE LIABLE TO YOU FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, CONSEQUENTIAL OR EXEMPLARY DAMAGES, INCLUDING BUT NOT LIMITED TO, DAMAGES FOR LOSS OF PROFITS, GOODWILL, USE, DATA OR OTHER INTANGIBLE LOSSES (EVEN IF THE  "OWNER" AND "MODERATORS" OF DIGITAL BW, THE PRINT YAHOO GROUP HAVE BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES), RESULTING FROM: (i) THE USE OR THE INABILITY TO USE THE DIGITAL BW, THE PRINT YAHOO GROUP; (ii) UNAUTHORIZED ACCESS TO OR ALTERATION OF YOUR TRANSMISSIONS OR DATA; (iii) STATEMENTS OR CONDUCT OF ANY THIRD PARTY ON THE DIGITAL BW, THE PRINT YAHOO GROUP; OR (iv) ANY OTHER MATTER RELATING TO THE DIGITAL BW, THE PRINT YAHOO GROUP.




------------------------------------------------------------------------------
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    a.. To visit your group on the web, go to:
    http://groups.yahoo.com/group/DigitalBlackandWhiteThePrint/
      
    b.. To unsubscribe from this group, send an email to:
    DigitalBlackandWhiteThePrint-unsubscribe@yahoogroups.com
      
    c.. Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service. 




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