Matching Sky Color between Multiple Images?

[rocknrory]

Hey everyone, I've spent the last hour or two trying to match the blue sky between two of my images. I looked up tutorials and discovered the "Match Color" adjustment, which helped, but is still quite noticeably off. Here's the original images without the Match Color adjustment:

I'd like to make the sky in the second image the color of the first palm image.

What do you recommend I do to get a precise match that looks balanced and natural?

Thanks!

[D Fosse]

You have much more urgent problems than color here. The sky in the second image is blown out and there's very little data to work with. In fact there's only useful data in the red channel - the blue and green are almost completely blown out.

Before you can start thinking about matching color, you need to consider tonality and that there's something to work with. There isn't here, unless you get to work on recreating values in the sky. If it's blown out, it's gone.

I know this isn't what you want to hear, but Photoshop can only work with what's there. If there is nothing, you need to rebuild. Obviously Photoshop can do that too, but that's a bit of work and no magic button.

[Norman Sanders]

D Fosse​ makes a whole lot of sense. He always does.

However, if you are limited to these two images with the criterion of matching the skies, you will derive a more authentic look if you avoid trying to make a creditable sky mask of the overexposed, flared sky and soft edged trees. That would mean making the darker sky lighter, rather than the lighter sky darker.

If that  is acceptable, then:

1. Make a sky mask of the darker image by building on an Alpha channel of the B channel.

2. Apply the mask to the darker image

3, Use the color sampler tool to read and mark the lighter image sky, as indicated below.

4. Switch to the darker image mark as shown and use Curves to match its RGB values to the lighter image. (The Info panel will record the Before and After reading of the adjustment.) Note that both samples now read R164 G209 B215

[Trevor.Dennis · Accepted solution]

Norman, I am hoping you have got it the wrong way round, because if you haven't, I have.

I also like to do it with numbers, because you don't need a superpower like Dag (who can identify every tone and shade of 16 bit Pro Photo RGB with his bear eyes!), so the first thing I did was lay a couple of colour sample points.

Note the source image is at the top of the stack, and unaffected by the adjustment layers beneath it.

I used Select > Colour Range to select the sky (left image only) and opened a Curves layer which automatically filled the layer mask with black for the non selected area.

I then used the RGB drop down, and selected in turn, the Red, Green, and Blue channels.

Select the little hand icon, and drag on the image (right where the colour sample point is) to place a point on the curve.

Then select the Curves output field for that point, and manually adjusted using the cursor keys.

I had to go round the three channels a couple of times to home in on a match.

This has left a magenta tinge in the clouds, so a Hue/Saturation layer was set to Magentas, and the saturation knocked out.

There is still some colour cast, which could probably be removed by fine tuning the colour sliders at the bottom of the Properties panel to expand the range of affect colour

Lastly the top right corner was too dark and standing out, so I fixed that with the Dodge tool set to Midtones.  A could of strokes at 10% opacity did the trick.

What is nice about this sort of approach, is there is less of the edge artefacts you'd find nearly impossible to avoid if you tried to drop in a new sky.  But there is still some.  I have reduced that with Mask Properties > Select & Mask moving shift edge well to the left, and adding the merest touch of feather.  Set the Output to Layer mask, and it will update the mask accordingly

I also fine tuned the Hue/Sat colour range by moving the left sliders as far left as I dared without impacting the blues, and moving the right sliders towards the orange and reds.  That completely takes out that magenta in the clouds.

Note you can't affect colour if there is none to affect.  Note also that pushing an image too far is likely to cause banding.  I can clearly see banding in my last screen shot.  Moving the image to 16bit before starting this process might have helped.  This is not my area of expertise though.  I Dag finds this thread then he knows more than me, but Prof Norman knows waaaaaay more than Dag .   We'll be able to hear Dag growling when he reads that.

[Trevor.Dennis]

Ahhhhh..   I'd missed that Dag had already posted to this thread.

[rocknrory]

Thank you for your time and detailed process! I achieved a similar result with the Match Color adjustment, but it was still decently off. It also made the sky look strange around the outline of the trees, as it does in your result in which you mentioned. It comes decently close, and I would like to match it in the way you attempted, yet based on others responses, it seems like that is the difficult way. I wish I shot the blown out image with a proper exposure; for the data, not for the lcd! I look at the lcd and see way too dark shadows and think I need to push the exposure, when the histogram really contains the truth.

I wish I could apply the palm tree sky color to the orange tree sky, as I want to match that to a series of images. In the end, I believe compromising is better in order to gain a more natural result.

You are very good at explaining what you did in great detail! I appreciate it.

[rocknrory]

Wow, you really matched the skies well! Could you explain to me what you mean by "Make a sky mask of the darker image by building on an Alpha channel of the B channel."? I haven't used channels much in PS.  Also, would this be the best method to work in reverse if the lighter image wasn't overexposed and had proper data?

Thank you!

[Norman Sanders]

OK. Here we go: Response to Post 36,,,

1. Make a sky mask of the darker image by building on an Alpha channel of the B channel...

***

Duplicate the image layer. Choose the Channels panel. Drag the B channel down to the "Create new channel" symbol at the bottom of the Channels panel. It becomes Blue copy. Use Levels to Increase contrast. It is now the Black & White Mask mask, ready to be applied.

2. Apply the mask to the darker image

***

Drag the Mask channel down to the "Load channel as a Selection" symbol at the bottom of the Channels panel. You will see marching ants in the Mask channel’s image.

Next, click on the RGB layer. The full color image will appear and the eye will click off next to the Mask channel.

Last, return to the Layers panel and click on the Mask symbol at the bottom of the Layers panel At this point, any change to that layer will only affect the sky.

  3, Use the color sampler tool to read and mark the lighter image sky, as indicated below.

***

Look at the Info panel. The RGB values will be displayed. Jot them down.

4. Switch to the darker image mark as shown and use Curves to match its RGB values to the lighter image. (The Info panel will record the Before and After reading of the adjustment.) Note that both samples now read R164 G209 B215)

***

Choose the image in the Layers panel of the top layer. (A frame willl appear around it.) Choose Curves. Hold down the Cmd+Shift keys and click on the marker in the iimage. Its values will appear on the individual RGB curves. Choose the Red channel within Curves and, using the north/south keyboard keys move the value to the one you jotted down earlier. Then move to the G and repeat. Then move to G and repeat.  Last, with the Color Sampler tool chosen, drag the markers out of the image.

ALSO:

"...would this be the best method to work in reverse if the lighter image wasn't overexposed and had proper data?" Yes. There are certain images where the basis for  a mask is located in a different Mode (CMYK or Lab Color) -- but I have found that whenever you use a Channel rather than a Brush to build a first rate mask, you're ahead of the game.

[rocknrory]

Gotcha, I'm learning it is better to treat the camera like a data capturing device and collect the best data than overexpose for the result I'm into at the moment. For a long time I've overly relied on my camera's LCD screen to judge exposure instead of the histogram, which is what I'm doing now. Typically I underexposure as I find it's easier to bring shadows up than highlights down. Ideally I would like to get excellent exposures right off the bat consistently.

Thanks for the reply, I appreciate learning from everyone who's commented!