Handling translucency is tough [challenge]

K1TesseraEna · **Joined:** Sep 22, 2012 **Posts:** 2089 **Location:** US

Change the black background color of the image below to white.

Don't say it's a piece of cake yet. The hardest part is to change the midtones 'behind'
ballerina's translucent chiffon tulle skirt without destroying the image and most importantly your computer :crash

I've done a 30-40 minutes work trying different approaches (color to alpha, messing with channels, gmic filters, color substitution, etc.)
The best I could come up with so far is this

If you have a recipe for doing such a task in the most efficient way in GIMP, please, come out and share your wisdom with us

Good luck!

P.S. To convince us there is indeed a translucency place an object of distinct color (e.g. blue) behind the skirt :bigthup

P.S.S. To track image integrity and changed BG behind the skirt open both images as layers in gimp

okyl168 · **Joined:** Jan 20, 2014 **Posts:** 66

This is what I tried
separate the background, filled with required color
separate the translucent area, filled with required color and overlay with lower opacity

Attachment:

2204_Ballerina_jump_red.png [ 151.6 KiB | Viewed 5638 times ]

Akros · **Joined:** Jan 10, 2013 **Posts:** 863

My attempt.
Masks, curves, and lots of patience

Issabella · **Posted:** Thu Jul 10, 2014 7:39 am **(#4)**

Akros, you got it! I love the atmosphere created and the translucent through the dress, great! :coolthup

sallyanne · **Posted:** Thu Jul 10, 2014 8:24 am **(#5)**

Well done Akros.

dinasset · **Posted:** Thu Jul 10, 2014 9:20 am **(#6)**

big success on the transparency side, Akros, congrats!
the remained problem if the black outline around the dancer (I did a try, but I've given up for this reason)

dinasset · **Posted:** Thu Jul 10, 2014 9:50 am **(#7)**

just not to give it up completely, here is my trial
used primarily the white original, to avoid the black contour

Attachment:

2204_01_Ballerina_DN1.png [ 1.36 MiB | Viewed 5560 times ]

K1TesseraEna · **Joined:** Sep 22, 2012 **Posts:** 2089 **Location:** US

Impressive results so far!
A few remarks.
@Akros Brilliant job on translucency! You nailed it! I have to agree with dinnaset though about black outline but it's just a matter of patience here.
Also great idea to use curves - I haven't thought about this!
@okyl168 good results, however, overlaying with color-filled layer may work sometimes but it colors the fabric of a skirt rather than the
background; imagine now that you have a customer who wants you to make a foreground selection so he can put any image on the background
that would show through the translucent areas of the skirt. Real translucency is a must in such cases. (images below)
@dinnaset nicely done, the only critique is that the selection of the background obviously grown 1-2 pxls to get rid of the black outline also shrank ballerina's fingers.

My attempts aren't perfect either so I just keep trying.

Real translucency [screenshot]

so that the BG can be easily replaced

K1TesseraEna · **Joined:** Sep 22, 2012 **Posts:** 2089 **Location:** US

Just an afterword.

In Photoshop this task is easy to achieve by selecting luminosity pixels by CTRL_clicking on RGB thumb in channels palette
then inverting the selection, cutting unwanted areas, copying luminosity pixels to a new layer and duplicating it several times
until the desired effect is achieved. Takes about 1 minute. No need for masks, fg or color selection and such.

I thought something similar was possible to do in GIMP. So far I haven't found the solution, and I was hoping someone would
come up with an idea. The final result can be achieved in GIMP but not quite that easy.

Akros · **Joined:** Jan 10, 2013 **Posts:** 863

K1TesseraEna wrote:

My attempts aren't perfect either so I just keep trying.
Real translucency [screenshot]

K1t

!
Excellent workmanship! :clap

Besides the necessary technical, you have plenty of patience! :bigthup

I tried a little polish black borders, but had lazy again. :gaah

K1TesseraEna wrote:

Just an afterword.

In Photoshop this task is easy to achieve by selecting luminosity pixels (...) The final result can be achieved in GIMP but not quite that easy.

I do not have Photoshop nor know tinkering with this software. But these times, seeing these features, gives a curiosity to test.
It was a good challenge, thanks for the suggestion! :hi5

dinasset · **Posted:** Thu Jul 10, 2014 2:06 pm **(#11)**

to stay on the game, w/o Photoshop
(c'est à dire: for my pleasure...)

Attachment:

2204_Ballerina_DN-2.png [ 1.21 MiB | Viewed 2701 times ]

RobA · **Joined:** Jul 14, 2010 **Posts:** 697

It would be easier if the original was converted from a jpeg, as there are some nasty artifacts in the areas around the dancer preventing a clean luminosity separation.

Here is the best I could do:

K1TesseraEna · **Joined:** Sep 22, 2012 **Posts:** 2089 **Location:** US

@Akros Now you're talking! Sorry if I made you sweat

Although it was not necessary because
you've done the hardest part just fine. P.S. I think patience is a skill too :lol

@dinnaset right on, excellente
@RobA you're right, :hehe

I spent a lot of time trying to find a good image for this exercise and it was not perfect.
My bad I should have cleaned the edges before posting :mrgreen:

Nice results, Rob. Must have been an easy ride for you.

I don't have photoshop, just happened to watch a video describing that technique and somehow it stayed on my mind for some time.
Finally got free tome to check things out in gimp.

A hint: I used gmic's Colors>Detect Skin filter as the base for further manipulations. This filter comes as close to PS luminosity
separation as any other filter (from the ones I tried)

dinasset · **Posted:** Fri Jul 11, 2014 5:17 am **(#14)**

playing again
this challenge is exciting...

Attachment:

2204_01_Ballerina_DN2.png [ 1.45 MiB | Viewed 2674 times ]

Issabella · **Posted:** Fri Jul 11, 2014 8:25 am **(#15)**

I agree with you K1TesseraEna, it has been a hard challenge for the best ones, here in the forum. All of their outcomes have been excellent. :jumpclap

Dinasset, I like your last one as you created a wonderful atmosphere.

trandoductin · **Posted:** Fri Jul 11, 2014 10:57 pm **(#16)**

This is difficult.
Here's my try using mask.
I just copied the dancer and pasted as a mask.
Then i used a brush and paint in full white to reveal the dancer, and use about 10% opacity white and paint over the translucent part many times until it look somewhat acceptable.

here's my .xcf

Attachment:

dancer_jumping.xcf [308.95 KiB]
Downloaded 149 times

wbool63 · **Posted:** Fri Jul 11, 2014 11:56 pm **(#17)**

trandoductin wrote:

This is difficult.
Here's my try using mask.
I just copied the dancer and pasted as a mask.
Then i used a brush and paint in full white to reveal the dancer, and use about 10% opacity white and paint over the translucent part many times until it look somewhat acceptable.
[ Image ]
here's my .xcf

Attachment:

dancer_jumping.xcf

probably the best outcome and the the simplest method. Nice

trandoductin · **Posted:** Fri Jul 11, 2014 11:57 pm **(#18)**

thanks wbool!

Akros · **Joined:** Jan 10, 2013 **Posts:** 863

Tin
Very nice!
You did a great job! :clap

Issabella · **Posted:** Sat Jul 12, 2014 3:01 am **(#20)**

Congratulations Tin. :clap