Saving Almost Blown Highlights -- Help Please

Discussion in 'Digital SLR' started by Douglas Johnson, Nov 2, 2005.

  1. I've got a picture that I like a lot:

    but the calligraphy and his hand are almost blown.

    I have the raw file. When I dial the exposure compensation way down (-2 stops),
    I get:

    so there is quite a bit of detail still there.

    How can I recover the calligraphy? Note that I don't have get the actual stuff
    in the picture. I'm willing to cut-paste-blend-whatever to get a reasonable

    I'm using Paint Shop Pro 9, but can get access to other tools if that will help.

    Douglas Johnson, Nov 2, 2005
    1. Advertisements

  2. Using those two images, and playing a little with the Gimp, I got this

    I placed both versions as separate layers in the same image, the dark
    image above the light one. Then I used a grayscale version of the
    light image as a layer mask for the dark layer, and tweaked the levels
    for the mask a bit. Something similar can probably be done in PSP.
    Måns Rullgård, Nov 2, 2005
    1. Advertisements

  3. Douglas Johnson

    nv Guest

    I've run them both through Photomatix Pro, and combined the two. But the
    highlights are still blown somewhat in the dialled-down version, hence you
    can't put back what ain't there to start with. :-(

    nv, Nov 2, 2005

  4. Can you post the raw file?
    Steve Franklin, Nov 2, 2005
  5. Douglas Johnson, Nov 2, 2005
  6. Here's the best I could get:

    RSE, 2 exposures in PS blended using the method Mans described. Set layer
    blending to Multiply, opacity about 90%, levels adjusted til the gradation
    looked more natural. I'm afraid those fingers are way too far gone, though-
    probably why this still looks a bit unnatural.

    Martin Francis, Nov 2, 2005
  7. Awesome result! Many thanks. I'll give it a try.

    -- Doug
    Douglas Johnson, Nov 3, 2005
  8. Douglas Johnson

    JPS Guest

    In message <>,
    I'm looking at the RAW data right now; all three color channels are
    clipped at the edge of the parchment right by the guy's finger's; as you
    get farther away from that on the parchment, the blue channel falls
    quickly below the clipping level (the edge of the parchment, is, in
    fact, the only area in the image where the blue channel is clipped).
    The bound book has green and red clipping in it, as well as the rest of
    the parchment in a circle that goes almost to the (calligrapher's) left
    edge of the parchment. Since the blue channel is only clipped in a
    small area, you could probably use its luminance to bring luminance back
    into the clipped areas with layering, and you could clone hue/saturation
    from the unclipped areas.

    Sounds like lots of work, but you could probably improve it some.

    JPS, Nov 3, 2005
  9. Thanks to everyone. I did just this. Here is my result:

    It was a educational experience.

    -- Doug
    Douglas Johnson, Nov 4, 2005
  10. Douglas Johnson

    jeff Guest

    jeff, Nov 4, 2005
  11. Douglas Johnson

    Paul Furman Guest

    I'm so glad to see that yellow gone. What exactly did you do for that?
    Paul Furman, Nov 4, 2005
  12. Douglas Johnson

    jeff Guest

    In Photoshop

    control layer
    the yellow was adjusted by a hue/saturation control layer see:

    I reduced the saturation of the yellow afte narrowring the selection
    to the shade of yellow of the hand. This had a side effect of bringing
    up the blue channel which still had detail of the hand (the detail in
    the red and green channels were mostly gone).

    Make sense?
    jeff, Nov 5, 2005
  13. Douglas Johnson

    nv Guest

    Jeff, that is truly astonishing at how much detail was still available in
    those 'blown' highlights. I too downloaded the original RAW file, but
    couldn't retrieve anything like that detail using the conventional exposure
    adjustments. That Hue/Sat trick in Photoshop is new on me ( as are most
    things digital!! LOL) and very useful to know. Your technique is bordering
    on the forensic, IMV! However, I can't practise with that image now as I
    have deleted it off my hard drive and the link is no longer available.
    :-( Still, I'm sure I can come up with some of my own..... somewhere....

    nv, Nov 5, 2005
  14. Douglas Johnson

    JPS Guest

    In message <>,
    That's a good idea, but to really extract the luminance of the blue
    channel completely, it is better to get the blue channel directly from
    the RAW data, without any RGB conversion or demosaicing, as the other
    channels will contaminate the blue channel with a normal conversion:

    JPS, Nov 5, 2005
  15. Wow! Wonderful detail. How you get blue channel out of the raw?
    Douglas Johnson, Nov 5, 2005
  16. Douglas Johnson

    Paul Furman Guest

    Yes, thanks. Drop down the yellow to apply desaturation.

    Holy crap! I played around and got something similar by adjusting white
    balance in the PS ACR converter, something I'd never tried before. But I
    couldn't get detail in the edge of the book beyond or reduce the
    contrast as much as your sample. How'd you do that?

    Hmmm, OK, playing some more, I converted it with DCRAW wide gamut &
    selecting the blue channel gets it perfect! I tried converting with ACR
    with much worse results, even as 16 bit, dropping the exposure to -4.

    Simply amazing what can be recovered!
    Paul Furman, Nov 5, 2005
  17. Douglas Johnson

    Paul Furman Guest

    How do you do that 'grayscale version of the light image as a layer
    mask' in PS? I used to know how but forgot.
    Paul Furman, Nov 5, 2005
  18. Douglas Johnson

    JPS Guest

    In message <>,
    Well, it was never really lost, just unused.

    This is why I have always said that greyscale images from RAW data
    should be done without demosaicing. Demosaicing is necessary for color
    images, but an obstacle to greyscale or extracting single channels.
    JPS, Nov 6, 2005
  19. Douglas Johnson

    G.T. Guest

    Wow is right. You can see his fingers without any problem.

    G.T., Nov 6, 2005
  20. Douglas Johnson

    G.T. Guest

    Would you mind outlining the steps taken to get that result?

    G.T., Nov 6, 2005
    1. Advertisements

Ask a Question

Want to reply to this thread or ask your own question?

You'll need to choose a username for the site, which only take a couple of moments (here). After that, you can post your question and our members will help you out.