Newbie: difference between Hue, Cast, Color balance and C. Temp?

Discussion in 'Digital Photography' started by ABC, Dec 5, 2004.

  1. ABC

    ABC Guest

    Newbie : How are these different in adjusting the colour of the pic.

    Thanks

    ABC
    Do not reply by email.
     
    ABC, Dec 5, 2004
    #1
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  2. ABC wrote:
    > Newbie : How are these different in adjusting the colour of the pic.
    >
    > Thanks


    In most photo-editing programs you can adjust the relative amounts of red,
    green and blue in the image. All of the functions you mentioned do
    basically the same thing, and alter the amount of R, G or B to achieve a
    particular effect, and the different names refer to different ways of
    making the adjustment.

    Colour temperature, for example, only has two controls: soure colour
    temperature and display colour temperature, and it /basically/ keeps the
    green constant whilst either increasing red and decreasing blue (to make
    the picture "warmer" - to look more like sunrise or sunset), or vice-versa
    to make an artificial light picture look more like daylight.

    I suggest you search for a good tutorial on the Internet, or find a book
    in your local bookshop about using e.g. Paint Shop Pro.

    Cheers,
    David
     
    David J Taylor, Dec 5, 2004
    #2
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  3. ABC

    Guest

    In message <>,
    "David J Taylor" <> wrote:

    >In most photo-editing programs you can adjust the relative amounts of red,
    >green and blue in the image. All of the functions you mentioned do
    >basically the same thing, and alter the amount of R, G or B to achieve a
    >particular effect, and the different names refer to different ways of
    >making the adjustment.


    True, except the hue. While the other just scale the RGB channels, a
    hue change actually will change the colors in such a way that is
    irreversible. Two different hues can become the same hue after a hue
    adjustment. Hue adjustment can result in 255 in a channel that
    originally had 0.
    --

    <>>< ><<> ><<> <>>< ><<> <>>< <>>< ><<>
    John P Sheehy <>
    ><<> <>>< <>>< ><<> <>>< ><<> ><<> <>><
     
    , Dec 5, 2004
    #3
  4. wrote:
    > In message <>,
    > "David J Taylor" <> wrote:
    >
    >> In most photo-editing programs you can adjust the relative amounts
    >> of red, green and blue in the image. All of the functions you
    >> mentioned do basically the same thing, and alter the amount of R, G
    >> or B to achieve a particular effect, and the different names refer
    >> to different ways of making the adjustment.

    >
    > True, except the hue. While the other just scale the RGB channels, a
    > hue change actually will change the colors in such a way that is
    > irreversible. Two different hues can become the same hue after a hue
    > adjustment. Hue adjustment can result in 255 in a channel that
    > originally had 0.


    I regard Hue adjustment as rotating things round a colour circle, and
    therefore as something which should be reversible. Depends on which
    program does the adjustment? My perception probably comes from too much
    involvement in colour TV!

    David
     
    David J Taylor, Dec 5, 2004
    #4
  5. David J Taylor wrote:

    > wrote:
    >
    >>In message <>,
    >>"David J Taylor" <> wrote:
    >>
    >>
    >>>In most photo-editing programs you can adjust the relative amounts
    >>>of red, green and blue in the image. All of the functions you
    >>>mentioned do basically the same thing, and alter the amount of R, G
    >>>or B to achieve a particular effect, and the different names refer
    >>>to different ways of making the adjustment.

    >>
    >>True, except the hue. While the other just scale the RGB channels, a
    >>hue change actually will change the colors in such a way that is
    >>irreversible. Two different hues can become the same hue after a hue
    >>adjustment. Hue adjustment can result in 255 in a channel that
    >>originally had 0.

    >
    >
    > I regard Hue adjustment as rotating things round a colour circle, and
    > therefore as something which should be reversible. Depends on which
    > program does the adjustment? My perception probably comes from too much
    > involvement in colour TV!
    >


    It's fully reversible in PS CS via an adjustment layer.

    --

    John McWilliams
     
    John McWilliams, Dec 5, 2004
    #5
  6. ABC

    Guest

    In message <>,
    "David J Taylor" <> wrote:

    >I regard Hue adjustment as rotating things round a colour circle, and
    >therefore as something which should be reversible. Depends on which
    >program does the adjustment? My perception probably comes from too much
    >involvement in colour TV!


    Photoshop's hue/saturation control will shift red to blue and leave blue
    where it is, for example.
    --

    <>>< ><<> ><<> <>>< ><<> <>>< <>>< ><<>
    John P Sheehy <>
    ><<> <>>< <>>< ><<> <>>< ><<> ><<> <>><
     
    , Dec 5, 2004
    #6
  7. wrote:
    > In message <>,
    > "David J Taylor" <> wrote:
    >
    >> I regard Hue adjustment as rotating things round a colour circle, and
    >> therefore as something which should be reversible. Depends on which
    >> program does the adjustment? My perception probably comes from too
    >> much involvement in colour TV!

    >
    > Photoshop's hue/saturation control will shift red to blue and leave
    > blue where it is, for example.


    Oh, in which case it's not operating how I would expect a hue control to
    operate. To me, hue is something which is measured in degrees (0..360)
    and would wrap round, so you could /not/ shift red without shifting blue
    as well.

    Cheers,
    David
     
    David J Taylor, Dec 5, 2004
    #7
  8. ABC

    bob Guest

    wrote in news::

    > Photoshop's hue/saturation control will shift red to blue and leave blue
    > where it is, for example.
    >


    Not in PS 6. If you make a blue fill, and bring image|adjust|hue &
    saturation, and if you turn on "preview", you can slide the hue slider back
    and forth and see every color of the rainbow.

    That's the default behavior. If you change the option on the dialog to
    "blues" instead of "master" then it will only change the blues, while
    leaving everything else alone.

    Bob

    --
    Delete the inverse SPAM to reply
     
    bob, Dec 5, 2004
    #8
  9. ABC

    Guest

    In message <>,
    "David J Taylor" <> wrote:

    > wrote:
    >> In message <>,
    >> "David J Taylor" <> wrote:
    >>
    >>> I regard Hue adjustment as rotating things round a colour circle, and
    >>> therefore as something which should be reversible. Depends on which
    >>> program does the adjustment? My perception probably comes from too
    >>> much involvement in colour TV!

    >>
    >> Photoshop's hue/saturation control will shift red to blue and leave
    >> blue where it is, for example.

    >
    >Oh, in which case it's not operating how I would expect a hue control to
    >operate. To me, hue is something which is measured in degrees (0..360)
    >and would wrap round, so you could /not/ shift red without shifting blue
    >as well.


    Even if all tools worked as you thought, hue would still be in a
    different class than color balance tools, as there is no way to go from
    0,255,0 to 0,0,255 in any of them.
    --

    <>>< ><<> ><<> <>>< ><<> <>>< <>>< ><<>
    John P Sheehy <>
    ><<> <>>< <>>< ><<> <>>< ><<> ><<> <>><
     
    , Dec 5, 2004
    #9
  10. ABC

    Guest

    In message <Xns95B6996B677CDbobatcarolnet@216.196.97.142>,
    bob <> wrote:

    >That's the default behavior. If you change the option on the dialog to
    >"blues" instead of "master" then it will only change the blues, while
    >leaving everything else alone.


    That is what I was talking about.
    --

    <>>< ><<> ><<> <>>< ><<> <>>< <>>< ><<>
    John P Sheehy <>
    ><<> <>>< <>>< ><<> <>>< ><<> ><<> <>><
     
    , Dec 5, 2004
    #10
  11. David J Taylor wrote:
    > wrote:
    >
    >>In message <>,
    >>"David J Taylor" <> wrote:
    >>
    >>
    >>>I regard Hue adjustment as rotating things round a colour circle, and
    >>>therefore as something which should be reversible. Depends on which
    >>>program does the adjustment? My perception probably comes from too
    >>>much involvement in colour TV!

    >>
    >>Photoshop's hue/saturation control will shift red to blue and leave
    >>blue where it is, for example.

    >
    >
    > Oh, in which case it's not operating how I would expect a hue control to
    > operate. To me, hue is something which is measured in degrees (0..360)
    > and would wrap round, so you could /not/ shift red without shifting blue
    > as well.
    >
    > Cheers,
    > David
    >
    >

    It depends on relative or absolute shift

    absolutely shift red to blue (and leave blue & green unaltered)

    relatively shift red and blue (relative to each other and leave green
    unaltered_

    relatively shift the color triangle by mapping R -> B B -> R G -> G
    and so forth (maybe even allowing G -> Y)

    Aerticeus
     
    Aerticulean Effort, Dec 5, 2004
    #11
  12. ABC

    ABC Guest

    In short, does it mean:

    Hue is to change the colour by turning a colour wheel, so that the
    color become the neighbouring one

    Cast is to add a chosen colour tint---I can add a red cast, right?

    Colour balance is to change cast by sliding it between blue to
    yellow. Same for C. temp.

    Or is that wrong??

    I use photoimpact 10. It has one control for color balance and one for
    cast. There must be something that makes them different.

    ABC
    Do not reply by email.
     
    ABC, Dec 6, 2004
    #12
  13. ABC

    bob Guest

    ABC <> wrote in news:nhd7r0loq6lc5ocp4unj361j2ap47gv6le@
    4ax.com:

    > In short, does it mean:
    >
    > Hue is to change the colour by turning a colour wheel, so that the
    > color become the neighbouring one


    Hue is a particular shade of color. Red is a hue, blue is a hue.

    > Cast is to add a chosen colour tint---I can add a red cast, right?


    Cast implies too much of a color. If you put a yellow filter in front of
    your lightbulbs, then your photos will have a yellow cast.


    Bob

    --
    Delete the inverse SPAM to reply
     
    bob, Dec 6, 2004
    #13
  14. ABC

    bob Guest

    wrote in news::


    > Even if all tools worked as you thought, hue would still be in a
    > different class than color balance tools, as there is no way to go from
    > 0,255,0 to 0,0,255 in any of them.


    Can you explain why you think that?

    If I make a graduated fill from 0,255,0 to 0,0,255 that fills left to right
    across a selection, then the info tool reports H,S,B at 120 degrees, 100%,
    99%, at the left edge, and 204,100,62 at the right edge. The H value goes
    up sequentially, while the S value dips and rises, and the B value
    generally falls.

    To my way of thinking, the hue works the way David describes, not in some
    other way that you seem to think.

    Bob


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    bob, Dec 6, 2004
    #14
  15. ABC

    Guest

    In message <Xns95B6E4485DE1Cbobatcarolnet@216.196.97.142>,
    bob <> wrote:

    > wrote in news::
    >
    >
    >> Even if all tools worked as you thought, hue would still be in a
    >> different class than color balance tools, as there is no way to go from
    >> 0,255,0 to 0,0,255 in any of them.

    >
    >Can you explain why you think that?


    Can you explain what it is that I "thought". Judging from your
    response, you did not understand what I wrote.

    We were talking about software functions that change the RGB values of
    pixels. I said that hue adjustment was in a different class of
    operations than color balance tools.

    Color balance tools change scaling. You can't scale any number greater
    than zero to zero, and you cant scale zero to sny number that is not
    zero.

    >If I make a graduated fill from 0,255,0 to 0,0,255 that fills left to right
    >across a selection, then the info tool reports H,S,B at 120 degrees, 100%,
    >99%, at the left edge, and 204,100,62 at the right edge. The H value goes
    >up sequentially, while the S value dips and rises, and the B value
    >generally falls.
    >
    >To my way of thinking, the hue works the way David describes, not in some
    >other way that you seem to think.


    --

    <>>< ><<> ><<> <>>< ><<> <>>< <>>< ><<>
    John P Sheehy <>
    ><<> <>>< <>>< ><<> <>>< ><<> ><<> <>><
     
    , Dec 6, 2004
    #15
  16. ABC

    Guest

    In message <>, I,
    wrote:

    >Color balance tools change scaling. You can't scale any number greater
    >than zero to zero,


    Well, you can if you scale it *by* zero, but that is not a normal color
    balance operation.
    --

    <>>< ><<> ><<> <>>< ><<> <>>< <>>< ><<>
    John P Sheehy <>
    ><<> <>>< <>>< ><<> <>>< ><<> ><<> <>><
     
    , Dec 6, 2004
    #16
  17. Aerticulean Effort wrote:
    []
    > It depends on relative or absolute shift
    >
    > absolutely shift red to blue (and leave blue & green unaltered)
    >
    > relatively shift red and blue (relative to each other and leave green
    > unaltered_
    >
    > relatively shift the color triangle by mapping R -> B B -> R G -> G
    > and so forth (maybe even allowing G -> Y)
    >
    > Aerticeus


    If you are using the normal definition of Hue (as in HLS, HSV etc.) then
    there is no such thing as absolute or relative shift as you describe it.
    Neither is there any way in which altering the Hue will leave /any/ colour
    unaltered.

    Perhaps some programs introduce the concept for special effects or
    marketing?

    David
     
    David J Taylor, Dec 6, 2004
    #17
  18. ABC

    ABC Guest

    On Sun, 05 Dec 2004 21:12:42 -0600, bob <>
    wrotd:

    >ABC <> wrote in news:nhd7r0loq6lc5ocp4unj361j2ap47gv6le@
    >4ax.com:
    >
    >> In short, does it mean:
    >>
    >> Hue is to change the colour by turning a colour wheel, so that the
    >> color become the neighbouring one

    >
    >Hue is a particular shade of color. Red is a hue, blue is a hue.
    >
    >> Cast is to add a chosen colour tint---I can add a red cast, right?

    >
    >Cast implies too much of a color. If you put a yellow filter in front of
    >your lightbulbs, then your photos will have a yellow cast.
    >

    Good definition. But can adjusting Hue also change 'Cast'?

    What exactly does the Hue adjustment do?

    ABC
    Do not reply by email.
     
    ABC, Dec 6, 2004
    #18
  19. ABC

    ABC Guest

    On Mon, 06 Dec 2004 04:26:52 GMT, wrotd:

    >Color balance tools change scaling. You can't scale any number greater
    >than zero to zero, and you cant scale zero to sny number that is not
    >zero.

    Oh, what on earth is that??


    ABC
    Do not reply by email.
     
    ABC, Dec 6, 2004
    #19
  20. ABC

    Guest

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