Small addition to Ron's e-book w/permission

[Tim Bessell]

Hi,

I got a lot of useful info from Ron Reznick's e-book. One part I found interesting and very useful was the section on how to set exposure by evaluating the luminosity of a color much like the camera does. In Ron's book are two images that are intended to teach this concept to the user. I wanted to print the color image to carry with me, but it needed to have the grey values printed to be useful in the field. I have done just that and Ron has ok'd me to share them with anyone who finds them useful.

Due to space constrains I can't upload tiff files, instead here are links to 300dpi jpegs just like the original files.

The color image is 550K
http://users.adelphia.net/~tbessell/large_RGB135_Grey_Values.jpg
the grey image 350k.
http://users.adelphia.net/~tbessell/large_Grey_Values.jpg

And two smaller version for display.





--
Tim Bessell

 

[Ozzy13]

Many Thanks!!

Rob

Hi,
I got a lot of useful info from Ron Reznick's e-book. One part I
found interesting and very useful was the section on how to set
exposure by evaluating the luminosity of a color much like the
camera does. In Ron's book are two images that are intended to
teach this concept to the user. I wanted to print the color image
to carry with me, but it needed to have the grey values printed to
be useful in the field. I have done just that and Ron has ok'd me
to share them with anyone who finds them useful.

Due to space constrains I can't upload tiff files, instead here are
links to 300dpi jpegs just like the original files.

The color image is 550K
http://users.adelphia.net/~tbessell/large_RGB135_Grey_Values.jpg
the grey image 350k.
http://users.adelphia.net/~tbessell/large_Grey_Values.jpg

And two smaller version for display.





--
Tim Bessell

 

[Bob Randall]

Thanks, Just what I was looking for. This will encourage me to look at and possibly buy the e-book.

Rob

Hi,
I got a lot of useful info from Ron Reznick's e-book. One part I
found interesting and very useful was the section on how to set
exposure by evaluating the luminosity of a color much like the
camera does. In Ron's book are two images that are intended to
teach this concept to the user. I wanted to print the color image
to carry with me, but it needed to have the grey values printed to
be useful in the field. I have done just that and Ron has ok'd me
to share them with anyone who finds them useful.

Due to space constrains I can't upload tiff files, instead here are
links to 300dpi jpegs just like the original files.

The color image is 550K
http://users.adelphia.net/~tbessell/large_RGB135_Grey_Values.jpg
the grey image 350k.
http://users.adelphia.net/~tbessell/large_Grey_Values.jpg

And two smaller version for display.





--
Tim Bessell

 

[R. Bond]

Hi,
I got a lot of useful info from Ron Reznick's e-book. One part I
found interesting and very useful was the section on how to set
exposure by evaluating the luminosity of a color much like the
camera does. In Ron's book are two images that are intended to
teach this concept to the user. I wanted to print the color image
to carry with me, but it needed to have the grey values printed to
be useful in the field. I have done just that and Ron has ok'd me
to share them with anyone who finds them useful.

Due to space constrains I can't upload tiff files, instead here are
links to 300dpi jpegs just like the original files.

The color image is 550K
http://users.adelphia.net/~tbessell/large_RGB135_Grey_Values.jpg
the grey image 350k.
http://users.adelphia.net/~tbessell/large_Grey_Values.jpg

And two smaller version for display.





--
Tim Bessell

--
http://www.pbase.com/rebond

 

[Tim Bessell]

Bob,

I'm not pushing the sales of Ron's book in any way, but the story behind these images will undoubtedly increase your percent of keepers.

Rob

Hi,
I got a lot of useful info from Ron Reznick's e-book. One part I
found interesting and very useful was the section on how to set
exposure by evaluating the luminosity of a color much like the
camera does. In Ron's book are two images that are intended to
teach this concept to the user. I wanted to print the color image
to carry with me, but it needed to have the grey values printed to
be useful in the field. I have done just that and Ron has ok'd me
to share them with anyone who finds them useful.

Due to space constrains I can't upload tiff files, instead here are
links to 300dpi jpegs just like the original files.

The color image is 550K
http://users.adelphia.net/~tbessell/large_RGB135_Grey_Values.jpg
the grey image 350k.
http://users.adelphia.net/~tbessell/large_Grey_Values.jpg

And two smaller version for display.





--
Tim Bessell

--
Tim Bessell

 

[Tim Bessell]

Hi,
I got a lot of useful info from Ron Reznick's e-book. One part I
found interesting and very useful was the section on how to set
exposure by evaluating the luminosity of a color much like the
camera does. In Ron's book are two images that are intended to
teach this concept to the user. I wanted to print the color image
to carry with me, but it needed to have the grey values printed to
be useful in the field. I have done just that and Ron has ok'd me
to share them with anyone who finds them useful.

Due to space constrains I can't upload tiff files, instead here are
links to 300dpi jpegs just like the original files.

The color image is 550K
http://users.adelphia.net/~tbessell/large_RGB135_Grey_Values.jpg
the grey image 350k.
http://users.adelphia.net/~tbessell/large_Grey_Values.jpg

And two smaller version for display.





--
Tim Bessell

--
http://www.pbase.com/rebond

--
Tim Bessell

 

[peters]

Not clear on how you use these. Can someone explain?

Hi,
I got a lot of useful info from Ron Reznick's e-book. One part I
found interesting and very useful was the section on how to set
exposure by evaluating the luminosity of a color much like the
camera does. In Ron's book are two images that are intended to
teach this concept to the user. I wanted to print the color image
to carry with me, but it needed to have the grey values printed to
be useful in the field. I have done just that and Ron has ok'd me
to share them with anyone who finds them useful.

Due to space constrains I can't upload tiff files, instead here are
links to 300dpi jpegs just like the original files.

The color image is 550K
http://users.adelphia.net/~tbessell/large_RGB135_Grey_Values.jpg
the grey image 350k.
http://users.adelphia.net/~tbessell/large_Grey_Values.jpg

And two smaller version for display.





--
Tim Bessell

--
http://www.pbase.com/rebond

--
Tim Bessell

 

[GaryK]

Thanks, Tim

When I was reading Ron's book, the exact idea crossed my mind. It's great that:

1) You took the time to do it;
2) Ron allowed you to share it; and
3) You did!

I can't wait to get home and print this out.

Gary

Hi,
I got a lot of useful info from Ron Reznick's e-book. One part I
found interesting and very useful was the section on how to set
exposure by evaluating the luminosity of a color much like the
camera does. In Ron's book are two images that are intended to
teach this concept to the user. I wanted to print the color image
to carry with me, but it needed to have the grey values printed to
be useful in the field. I have done just that and Ron has ok'd me
to share them with anyone who finds them useful.

Due to space constrains I can't upload tiff files, instead here are
links to 300dpi jpegs just like the original files.

The color image is 550K
http://users.adelphia.net/~tbessell/large_RGB135_Grey_Values.jpg
the grey image 350k.
http://users.adelphia.net/~tbessell/large_Grey_Values.jpg

And two smaller version for display.





--
Tim Bessell

 

[Baracus]

I can't thank you enough for doing this. I was wanting the exact same thing. Now if you could just create a color file with the RGB values and the grey values in each square I'll be all set
--
It's All Relative,
Baracus
http://www.pbase.com/baracus

 

[R Laing]

There is a slight shift in value when I use color picker in PS7. Is this due to your color space when saved or is it the differance between CS & PS7?

tia

 

[Ron Reznick]

I checked Tim's originals in Pshop 6 and CS and found discrepancies between the originals and my own read in both pieces of software, but no discrepancies between PS6 and PS-CS. Tim redid the files based on my info, but it's possible that the JPG saves from his MAC altered values (I need to check the full-res files). The difference in his originals was likely due to slight differences in MAC and PC versions of Photoshop.

Ron

There is a slight shift in value when I use color picker in PS7.
Is this due to your color space when saved or is it the differance
between CS & PS7?

tia

--
Ron Reznick
http://digital-images.net
http://trapagon.com

 

[R Laing]

Thanks Ron.

There should be no difference in [value] between Mac & PC in value?!?

R100 B100 G100 is grey, yes?! R255 G255 B 0 is yellow.

I receive the same value in PS7 and Corel Paint even though the perceived color is completely different.

 

[Iliah Borg]

In NTSC color space (stands for "Never the Same Color" luminosity is approximatly:
L = 0.299 * R + 0.587 * G + 0.114 * B

If color matrix metering is used, it also takes care of this formula calculating average brightness, but with respectful correction to color information:

http://www.nikon.co.jp/main/eng/society/tec-rep/ccd.htm

So, why 25%R+50%G+25%B?

--
no text

 

[Vtie]

In NTSC color space (stands for "Never the Same Color" luminosity
is approximatly:
L = 0.299 * R + 0.587 * G + 0.114 * B

There is one major weakness of this formula: the definition of the R,G,B
values. The only purpose of this formula is to recode the RGB values
into YIQ for efficient transmission and compatibility with BW televisions.
However, what color model is used for the RGB values? This is not
necessarily equal to the sRGB model used by cameras, and definetely
not equal to Adobe RGB.

The numbers I usually use are 0.265*R+0.670*G+0.065*B.
Unfortunatey, I don't know anymore where I got them from, but
this is what I use if I need to convert R,G,B values to luminances.
At least, they are close to the NTSC ones and seem to agree upon
the fact that blue should be even weaker than red (and of course
green is the strongest).

Vtie
http://www.pbase.com/vtie

 

[Tim Bessell]

The point in Ron's book is about how the camera calculates luminosity using the Bayer pattern. Of course most of this is way over my head. I just need a rough idea of how to set exposure for a particular scene.

In NTSC color space (stands for "Never the Same Color" luminosity
is approximatly:
L = 0.299 * R + 0.587 * G + 0.114 * B

There is one major weakness of this formula: the definition of the
R,G,B
values. The only purpose of this formula is to recode the RGB values
into YIQ for efficient transmission and compatibility with BW
televisions.
However, what color model is used for the RGB values? This is not
necessarily equal to the sRGB model used by cameras, and definetely
not equal to Adobe RGB.

The numbers I usually use are 0.265*R+0.670*G+0.065*B.
Unfortunatey, I don't know anymore where I got them from, but
this is what I use if I need to convert R,G,B values to luminances.
At least, they are close to the NTSC ones and seem to agree upon
the fact that blue should be even weaker than red (and of course
green is the strongest).

Vtie
http://www.pbase.com/vtie

--
Tim Bessell

 

[Iliah Borg]

In NTSC color space (stands for "Never the Same Color" luminosity
is approximatly:
L = 0.299 * R + 0.587 * G + 0.114 * B

There is one major weakness of this formula: the definition of the
R,G,B
values.

As far as I know, it was defined for the responce of phosphors, so we have here some color space

The only purpose of this formula is to recode the RGB values
into YIQ for efficient transmission and compatibility with BW
televisions.

Initially, yes, it was.But when I experimented with in-camera histogram, it is pretty close.

However, what color model is used for the RGB values? This is not
necessarily equal to the sRGB model used by cameras, and definetely
not equal to Adobe RGB.

sRGB or Adobe RGB is output color space. Looks like they are not sensor color spaces.

The numbers I usually use are 0.265*R+0.670*G+0.065*B.
Unfortunatey, I don't know anymore where I got them from, but
this is what I use if I need to convert R,G,B values to luminances.
At least, they are close to the NTSC ones and seem to agree upon
the fact that blue should be even weaker than red (and of course
green is the strongest).

I would try the formula you've suggested. It is close to NTSC, as you said. Actually, I was not trying to provide any particular formula - I was just asking why .25R+.5G+.25B is used for luminosity evaluation. IMHO for each particular sensor having the access to RAW data the appropriate formula can be derived, if nessessary.

--
no text

 

[Ron Reznick]

Well, that is the only thing we could think of (difference in reading values in the Info Palette between Pshop CS on MAC and PC).

I tested in Photoshop 6 and 8 (CS) on the PC. The values were the same, but both were different than those shown on the file as measured in Pshop CS on the MAC.

Ron

Thanks Ron.

There should be no difference in [value] between Mac & PC in value?!?

R100 B100 G100 is grey, yes?! R255 G255 B 0 is yellow.

I receive the same value in PS7 and Corel Paint even though the
perceived color is completely different.

--
Ron Reznick
http://digital-images.net
http://trapagon.com

 

[Iliah Borg]

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no text

 

[alabaster]

--
no text

Your point being what? Can you elaborate?
--
Alabaster

 

[Iliah Borg]

Your point being what? Can you elaborate?

No point at all. Just visualisation of how sensor reproduces CC. Compare it to CC in color...
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no text