I need a blue sky quick!

[scottbergerphoto]

If you need a blue sky, but the one in your picture is kind of drab, here's are 2 quick and easy ways to blue it up:

1. Fast and easy
A. Open Photo
B. Make a copy of the original CTRL-J
C. Image>Adjustments>Color Balance
D. Push up the Cyan and Blue to make the sky look bluer. Don't worry about the rest of the picture.
E. Click X to make the foreground color black.
F. In the Layers palate, click ALT+ New Layer Mask icon. This creates a new Layer Mask and fills it with black to hide the color changes you just made.
G. Click X until the foreground color changes to white.
H. Use the Brush Tool to paint in the color correction. If you make a mistake, change the foreground color to black (type X), and paint it away.
I. Adjust the opacity of your layer to adjust the intensity of the correction.

2. I've got lots of pictures of just blue skies!
A. Open Photo
B. Use whatever selection tools you have to, to make a selection of the sky you want to replace.
C.Open the picture of the sky you want to use.
D. CTRL-C, to copy the new sky.
E. Make your original picture active, Edit>Paste Into. It will go automatically into the selection you made on a new layer.
F. Use the Opacity slider and the Blend Mode to acheive the results you like.
Source: Photoshop CS for Digital Photographers by Scott Kelby
Scott

[grandad35]

I have found that any range of blue sky colors can be quickly defined by creating a color using the CMYK inputs in the color picker with the Magenta set to (cyan value-25%) and the yellow and black both set to 0. A Cyan of 100% (Magenta=75%) gives a very dark sky and a Cyan of 25% (Magenta=0) gives a very light sky. The attached image shows a linear gradient between these two colors.

I have also found that most "sky shots" have about 10-15% less Cyan at the horizon than at a 30 degree elevation, so you should use a gradient to create a more realistic sky.

[scottbergerphoto]

I have found that any range of blue sky colors can be quickly defined by creating a color using the CMYK inputs in the color picker with the Magenta set to (cyan value-25%) and the yellow and black both set to 0. A Cyan of 100% (Magenta=75%) gives a very dark sky and a Cyan of 25% (Magenta=0) gives a very light sky. The attached image shows a linear gradient between these two colors.

I have also found that most "sky shots" have about 10-15% less Cyan at the horizon than at a 30 degree elevation, so you should use a gradient to create a more realistic sky.
Sounds interesting. Could you describe step by step how you would use this to replace a sky?
Thanks,
scott

[grandad35]

The first image shows a building with an overcast sky, alongside a version with the sky replaced with a color gradient from 50/25/0/0 (CMYK) at the top to 35/15/0/0 at the bottom. The building has the wrong lighting for a sunny day, so I brightened it up a bit. The building is still far from perfect, but the point was to show a "new sky", not how to change the lighting on a building. Note how the sky being lighter close to the horizon matches nature better than a solid color.

The second image was generated by adding a "clouds" layer with white and (50/25/0/0) as the two colors. A gradient layer from 60/35/0/0 to 25/0/0/0 with a 40% opacity was added on top to give a color gradient to the clouds. I pushed the color difference to 35% Cyan to account for the 40% reduction due to the opacity setting, giving an effective 14% difference (0.4 x 35%) in the Cyan level.

What do you think?

[kawter2]

I think it looks too fake

[scottbergerphoto]

The first image shows a building with an overcast sky, alongside a version with the sky replaced with a color gradient from 50/25/0/0 (CMYK) at the top to 35/15/0/0 at the bottom. The building has the wrong lighting for a sunny day, so I brightened it up a bit. The building is still far from perfect, but the point was to show a "new sky", not how to change the lighting on a building. Note how the sky being lighter close to the horizon matches nature better than a solid color.

The second image was generated by adding a "clouds" layer with white and (50/25/0/0) as the two colors. A gradient layer from 60/35/0/0 to 25/0/0/0 with a 40% opacity was added on top to give a color gradient to the clouds. I pushed the color difference to 35% Cyan to account for the 40% reduction due to the opacity setting, giving an effective 14% difference (0.4 x 35%) in the Cyan level.

What do you think?


Can you give step by step how to do it?
scott

[grandad35]

I think it looks too fake
As I said in my original post, the lighting on the building doesn't match the sky. Our eyes and brain immediately see this discrepancy and let us know that something is wrong.

Fortunately the sun is shining today and I have some blue sky to work with. I took a picture of some clear sky on a 300D at f2.8 (to hide the dirt on my sensor), ISO100, 1/3500 sec with AWB on. It was a little dark, so I lightened it up a little with "levels" to look like the "real" sky, but I did not touch any color adjustments. I looked at the colors at the top and bottom and generated a 75/45/0/0 ==> 45/20/0/0 gradient and put it alongside for comparison. The image on the right (with a little bit of tree) is obviously "real" and the one on the left is "fake". This comparison shows that nature uses a non-linear gradient, but the color match isn't all that bad for something that can easily remembered and quickly pulled out of thin air when needed.

This is not meant to replace other methods, only to give yet another way to do something similar that may come in handy some time in the future.

[grandad35]

Can you give step by step how to do it?
scott

Scott - Here goes. This may seem horribly complicated, but it's not so bad if you are already familiar with the various commands. I added a lot of detail just in case someone isn't familiar with some of the commands.
1. Start as your #2 does - make a selection of the sky that you want to replace. You can feather or not at this time (Ctrl-Alt-D), depending on the what is going on at the edges of the selection. A sharp transition to the sky needs only a little feathering - a fuzzy transition in small branches/tall grass/ etc. may need more feathering. Don't worry if the selection isn't perfect at this stage - it can be corrected in step 12.
2. In the Layers Palette, click the "Create a New Layer" icon to create an empty layer. It's not a bad idea to name it by double clicking on the layer
3. Make sure that the selection is still active, and click the "Add layer Mask" icon. The mask will be white where the sky was selected.
4. Click on the blank image thumbnail in the new layer to make it active.
5. Click on the foreground color swatch to activate the color picker. Make your color selection by clicking on the "Cyan" box and enter a value for the desired color at the top of the sky in this image, based on how dark you want the sky. Set "M" to "C"-25, and set "Y" and "B" to 0. Click "OK".
6. Repeat for the background color swatch, selecting the color that you want at the bottom of the sky that will appear in this image.
7. Select the "Gradient" tool ("G") - Make sure that you don't get the paint bucket that is on the same command.
8. Select the linear gradient (the leftmost of the 5 icons on the menu bar).
9. Click the dropdown menu just to the left of the icons on the menu bar and select the "Foreground to Background" icon (on the top/left).
10. Click in the image near the top of the sky. Hold the left mouse button down and move the cursor to the bottom of the sky. Holding the Shift key down during this step will keep the selection vertical (or horizontal, or 45 degrees, whichever is closer). Unless the photo was taken at an angle, you probably want the gradient to be vertical. When you let go of the left mouse button, the gradient will be generated. Any areas above the top selection point will have the foreground color and any areas below the bottom selection point will have the background color.
11. If you don't like the colors, you can select new colors and repeat step 10 until you are happy with the colors.
12. Clean up the selection. The reason for using a layer mask on the sky layer is that you can now go back and touch up the layer mask to modify the selection. Feathering can be controlled by the size and hardness of the brush, as well as by the opacity/flow. You can also reverse anything by painting the mask with white or black.


If you want to add clouds:
1. Repeat steps 1-4 above. Steps 5 and 6 are similar to the previous steps. Select the same sky color that you plan on using for the foreground, but select white for the background.
7. Select "Filter==>Render==>Clouds". This will generate a cloud pattern using the foreground and background colors. You can get additional patterns by repeating this filter (Shortcut = Ctrl-F). Repeat until you like the pattern. You might also want to try "Filter==>Render==>Difference Clouds". The first time that you do this, expect a horrible black/white display. Run it again (Same shortcut = Ctrl-F) and things will look a lot better. You can get additional patterns by running this command twice until you see something that you like. It is up to personal taste which filter to use.
8. Same as step 12 above. Because we will be copying this layer mask in the next step, the cleanup should be done before we copy it so that both masks are the same.
9. Copy the layer and mask (Ctrl-J). Set the opacity for the new layer to 40-60% (or to suit). Click on the image thumbnail in the new layer to make it active.
10-16. Repeat steps 5-11 above, using a larger color difference to compensate for the lowered opacity. This will put a color gradient on top of the cloud layer.

[PhotosGuy]

Um, why not keep a file of sky shots to use when you need them? (Put them in a folder next to your tree shots, etc) ;-)

[DReb-MO]

If you need a blue sky, but the one in your picture is kind of drab, here's are...

Thanks. This works great. I just wish I would have seen this before I sent a 5 pic pano off to the lab for printing yesterday. I was not 100% satisifed with the sky. Live and learn. Got tips for making clouds more pronounced? I tried increasing the contrast in a selection and increasing the brightness etc with unsatisfactoery results.

[grandad35]

Got tips for making clouds more pronounced? I tried increasing the contrast in a selection and increasing the brightness etc with unsatisfactoery results.

It seems that the clouds filter doesn't scale to the image size. It creates a pattern with lots of small clouds when you have lots of pixels and fewer large clouds when you have a low pixel count image. You might want to try creating a new image scaled to your image with (say) 500 pixels in its major direction, generating the clouds and sky, and then resizing it up to match your final image. I find that "Levels" generally works better than brightness/contrast to adjust the lighting levels in this situation. You can "fill out" the clouds by bringing in the right slider, adjust the intensity of the clear sky between the clouds with the left slider and adjust the transition between the two with the middle slider. Of course, you can do even more with "Curves".

HTH.

[DReb-MO]

Of course, you can do even more with "Curves".HTH.

One of the few parts of PS_CS I have not used or understand.

[scottbergerphoto]

One of the few parts of PS_CS I have not used or understand.
Try this. Curves is your friend.
http://www.photography-on-the.net/forum/showthread.php?t=62757

Scott

[colliewalker1]

If you need a blue sky, but the one in your picture is kind of drab, here's are 2 quick and easy ways to blue it up:


2. I've got lots of pictures of just blue skies!
A. Open Photo
B. Use whatever selection tools you have to, to make a selection of the sky you want to replace.
C.Open the picture of the sky you want to use.
D. CTRL-C, to copy the new sky.
E. Make your original picture active, Edit>Paste Into. It will go automatically into the selection you made on a new layer.
F. Use the Opacity slider and the Blend Mode to acheive the results you like.
Source: Photoshop CS for Digital Photographers by Scott Kelby
Scott


I have tried this method - it has worked OK except that having tried several skies all of them cover only part of the original sky!:rolleyes:

Does some sort of adjustment need to be made to the replacement sky?

[scottbergerphoto]

What do you have the Opacity Slider set at? 100%
Is the Blend Mode set to Normal?
Scott

[colliewalker1]

What do you have the Opacity Slider set at? 100%
Is the Blend Mode set to Normal?
Scott

Hi again Scott -

I am a real innocent when it comes to layers - I hadn't realised that with this procedure Layers would be involved: I have now activated the previously invisible Layers Box and found that although it was greyed out, Opacity did show 100%.

On looking into the meaning of 'Opacity' and 'Blend' I am just wondering if we might be at cross purposes here, as I can't see how they relate to a 'sky transfer' which shows the complete sky image but one which fails to fill the entire selected area -just a neat rectangle within it.

Interestingly, I have just tried Paintshop Pro using 'Copy and Paste' which doesn't seem to involve layers and which achieves a complete replacement of the original sky.:rolleyes:

[robertwgross]

Scott, I finally took your advice and purchased the Kelby book.

Now, just give me a decade or two to read through it all.

I confess, I have been mostly a Corel user for years, and it has only been within the last month that I've gotten Adobe Photoshop CS.

---Bob Gross---

[PhotosGuy]

I think the size/resolution of your sky pic is smaller than the base pic & you can make it larger using Edit > Transform. It might not look right when you do that since you'll be blowing it up.
When you have nothing better to do, it's a good idea to take some high resolution pics of skies, trees, etc for those times when you need a background.