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  • #263589
    Profile photo of ptleeptlee
    Participant

    I did a demo on alternative ways to improve a photo, and LAB provided a quick and easy way to salvage those flat & washout look of landscapes, especially those taken under hazy days, when colours are less than spectacular.

    The following is an example of what I did with Tony Png’s landscape to improve on the colours and contrast in a few easy to remember steps.
    Original Image from Topic

    1) Open the image in Photoshop CS.
    2) Change to LAB mode by selecting, from the menu, Image->Mode->Lab Color
    3) From the Histogram, the image appears a little dark, so adjust the tones brighter using levels and shift the white point arrow to the left (from Image->adjustments->levels

    The photo should appear now appear brighter.

    4) Now open curves from menu, Image->Adjustments->Curves
    5) Select the channel ‘a’ from the curves adjustment window

    6) shift the top right point left about 2.5 squares and bottom left points right similarly.
    use the mouse pointer, click on the point and drag across, keeping the ‘curve’ symmetrical as shown.

    7) Similarly, from the curves adjustment window, select the ‘b’ channel

    8) and shift the curve similarly as in (6)

    9) The image should now have pretty good contrast and colour saturation, next step, sharpening in Lab…

    capture01-LevelsAdjust.gif
    capture02-CurvesAdjust.gif
    capture03-CurvesAdjust.gif
    capture04-CurvesAdjust.gif
    capture05-CurvesAdjust.gif
    _9305840_1_800n_curveadjust.jpg

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    #296338
    Profile photo of ptleeptlee
    Participant

    10) Next we do sharpening, but only in the lightness channel

    11) From the layers window, select the ‘Channels’ tab to show the Lab, Lightness, a & b channels.
    SNPY 2017 Scoreboard UM

    12) Select just the Lightness channel, to reveal a monochrome image
    SNPY 2017 Scoreboard UM

    13) Now apply your normal USM (Unsharp mask) or sharpening task on this channel only.
    Filter->Sharpen->Unsharp Mask…
    SNPY 2017 Scoreboard UM

    14) from the channels tab, click on Lab to show the image in full colours again
    SNPY 2017 Scoreboard UM

    15) Now change back to RGB mode from the menu
    Image->Mode->RGB Color

    16) Save the image in jpeg. Voila!

    Hope this is useful.

    Cheers,
    PTLee
    capture06-sharpen.gif
    capture07-sharpen.gif
    capture08-sharpen.gif
    capture09-sharpen.gif
    _9305840_1_800n_final.pg.jpg

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    #296350
    Profile photo of tanhbtanhb
    Spectator

    Thanks for sharing. :kudos thumbsup:

    #296557
    Profile photo of wltpchwltpch
    Member

    Hi PT
    Thanks a lot!

    Cheers,
    Loong Tat

    #296642
    Profile photo of hanYeo, Wee Han
    Spectator

    Thanks PT. I read about LAB mode some years back but never tried it…. :ashamed: Looks like its worth exploring!

    Cheers

    Han

    #296646
    Profile photo of ptleeptlee
    Participant

    Yes, Han. I think it is worth exploring, esp for landscapes.

    I like the sharpening in the lightness channel, and the quick adjustments for contrast and colours is good for a quick proofing. It’s even good for old photo restoration, and high noise reduction.

    Cheers,
    PTLee

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