HDR mask to seperate just sky & land?

A
Posted By
asnowfall
May 22, 2006
Views
408
Replies
4
Status
Closed
I want to merge two pictures. But my requirements make it not so easy. Most of HDR techniques take whole frame in to account to generate mask. I do not want to that. I use merging for landscape pictures which have sky & land.
I would like to generate mask which seperatessky & land. Mask should have 100% black for sky and 100% white for land.

Let me explain this with an example….
Assume a frame with sky, mountain and lake(with little glare). Glare on the lake may be
nearly as bright as sky, but I would like mask to ignore the glary lake when generating mask.
Final mask should be provide demarkation between sky & land.

Currently I use a crude method to do this.
1) Convert the image to Grayscale
2) Use "Threshold" to generate mask. The threshold value that I use would have a value of the *darkest* cloud near the the horizon.
4) Apply Gaussian blur to above generated mask.
3) Use above generated mask for merging the image.
4) Use the ‘stamp’ tool to polish horizon.

Problems with above method…..
Mask would not be perfect and it leaves hightlights along the horizon. I need to do some ‘cloning’ to correct this.

Another solution….
Can I generate a mask with opacity of 50% near the horizon and gradually increas to 100%?

Please let me know if there are better ways to do this.

Thanks
Ramesh

Note: I am novice in Adobe PS. If you have any idea please give precise ket strokes 🙂

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K
KatWoman
May 24, 2006
wrote in message
I want to merge two pictures. But my requirements make it not so easy. Most of HDR techniques take whole frame in to account to generate mask. I do not want to that. I use merging for landscape pictures which have sky & land.
I would like to generate mask which seperatessky & land. Mask should have 100% black for sky and 100% white for land.

Let me explain this with an example….
Assume a frame with sky, mountain and lake(with little glare). Glare on the lake may be
nearly as bright as sky, but I would like mask to ignore the glary lake when generating mask.
Final mask should be provide demarkation between sky & land.
Currently I use a crude method to do this.
1) Convert the image to Grayscale

2) Use "Threshold" to generate mask. The threshold value that I use would have a value of the *darkest* cloud near the the horizon.

4) Apply Gaussian blur to above generated mask.
3) Use above generated mask for merging the image.
4) Use the ‘stamp’ tool to polish horizon.

Problems with above method…..
Mask would not be perfect and it leaves hightlights along the horizon. I need to do some ‘cloning’ to correct this.

Another solution….
Can I generate a mask with opacity of 50% near the horizon and gradually increas to 100%?

Please let me know if there are better ways to do this.

Thanks
Ramesh

Note: I am novice in Adobe PS. If you have any idea please give precise ket strokes 🙂

Can I generate a mask with opacity of 50% near the horizon and gradually increase to 100%?

after you create the rough mask use the wand to make it nicer, use feather to soften the edges, you can use a black to clear gradient ON THE MASK itself to graduate the blend

you may have better results using the magnetic lasso for your original selection, it has a bit more control, try it, it’s on a flyout of the lasso tool.
Why do you convert to greyscale?? why use threshold?

If the mask isn’t what you want, delete it and then make a selection then click the mask icon for a new one based on the selection. don’t clone on your image itself, you can paint or erase on the mask itself with the paintbrush set to black and white
A
asnowfall
Jun 6, 2006
Sorry for delayed response.
Why do you convert to greyscale?? why use threshold?
I use Gray scale image as starting point for mask generation because mask is gray scale image. I use threshold to generate rough mask. As I said, I am not an expert in Adobe and there may be other better ways to do it.

You wrote..
you can use a black to clear gradient ON THE MASK
itself to graduate the blend
Could you please explain this?
How do I apply gradient on the MASK at the juction of
100% black & 100% white?

BTW: I purchased Wacom Intuos tablet. This should help selection.

Thanks
Ramesh

KatWoman wrote:
wrote in message
I want to merge two pictures. But my requirements make it not so easy. Most of HDR techniques take whole frame in to account to generate mask. I do not want to that. I use merging for landscape pictures which have sky & land.
I would like to generate mask which seperatessky & land. Mask should have 100% black for sky and 100% white for land.

Let me explain this with an example….
Assume a frame with sky, mountain and lake(with little glare). Glare on the lake may be
nearly as bright as sky, but I would like mask to ignore the glary lake when generating mask.
Final mask should be provide demarkation between sky & land.
Currently I use a crude method to do this.
1) Convert the image to Grayscale

2) Use "Threshold" to generate mask. The threshold value that I use would have a value of the *darkest* cloud near the the horizon.

4) Apply Gaussian blur to above generated mask.
3) Use above generated mask for merging the image.
4) Use the ‘stamp’ tool to polish horizon.

Problems with above method…..
Mask would not be perfect and it leaves hightlights along the horizon. I need to do some ‘cloning’ to correct this.

Another solution….
Can I generate a mask with opacity of 50% near the horizon and gradually increas to 100%?

Please let me know if there are better ways to do this.

Thanks
Ramesh

Note: I am novice in Adobe PS. If you have any idea please give precise ket strokes 🙂

Can I generate a mask with opacity of 50% near the horizon and gradually increase to 100%?

after you create the rough mask use the wand to make it nicer, use feather to soften the edges, you can use a black to clear gradient ON THE MASK itself to graduate the blend

you may have better results using the magnetic lasso for your original selection, it has a bit more control, try it, it’s on a flyout of the lasso tool.
Why do you convert to greyscale?? why use threshold?

If the mask isn’t what you want, delete it and then make a selection then click the mask icon for a new one based on the selection. don’t clone on your image itself, you can paint or erase on the mask itself with the paintbrush set to black and white
K
KatWoman
Jun 7, 2006
wrote in message
Sorry for delayed response.
Why do you convert to greyscale?? why use threshold?
I use Gray scale image as starting point for mask generation because mask is gray scale image. I use threshold to generate rough mask. As I said, I am not an expert in Adobe and there may be other better ways to do it.

You wrote..
you can use a black to clear gradient ON THE MASK
itself to graduate the blend
Could you please explain this?
How do I apply gradient on the MASK at the juction of
100% black & 100% white?

BTW: I purchased Wacom Intuos tablet. This should help selection.
Thanks
Ramesh

Assuming this is a color landscape type image
use the magnetic lasso to separate the sky and land, or use Select>color range, clean up the selection using the wand, try various tolerances, add and subtract options of the tool, tick contiguous.
To check the selection click the mask icon in the tool bar, you may wish to touch up with the brush. Once you have a good selection, you may wish to soften using select feather or smooth. Always check the mask edges, making a good mask will not leave the bad matched edges in your final.

When the selection looks good, go to layers palette and click the mask icon. part of it will be white and part of it black. Click on the mask icon to make sure you are working on the mask not the image. Put the colors on default (black & white) choose the gradient tool. If you are working on the black area of the mask use the white to transparent gradient, make sure it’s set on linear, pull the gradient (hold down mouse button and drag) only on the area you wish to effect, the gradient does not have to go over the entire layer.
This should give you a smoother transition area.

I am sorry I didn’ t realize you are working in HDR I think it’s 16 bit? some tools are not available unless you switch mode to 8 bit (I am not too sure about HDR)

KatWoman wrote:
wrote in message
I want to merge two pictures. But my requirements make it not so easy. Most of HDR techniques take whole frame in to account to generate mask. I do not want to that. I use merging for landscape pictures which have sky & land.
I would like to generate mask which seperatessky & land. Mask should have 100% black for sky and 100% white for land.

Let me explain this with an example….
Assume a frame with sky, mountain and lake(with little glare). Glare on the lake may be
nearly as bright as sky, but I would like mask to ignore the glary lake when generating mask.
Final mask should be provide demarkation between sky & land.
Currently I use a crude method to do this.
1) Convert the image to Grayscale

2) Use "Threshold" to generate mask. The threshold value that I use would have a value of the *darkest* cloud near the the horizon.

4) Apply Gaussian blur to above generated mask.
3) Use above generated mask for merging the image.
4) Use the ‘stamp’ tool to polish horizon.

Problems with above method…..
Mask would not be perfect and it leaves hightlights along the horizon. I need to do some ‘cloning’ to correct this.

Another solution….
Can I generate a mask with opacity of 50% near the horizon and gradually increas to 100%?

Please let me know if there are better ways to do this.

Thanks
Ramesh

Note: I am novice in Adobe PS. If you have any idea please give precise ket strokes 🙂

Can I generate a mask with opacity of 50% near the horizon and gradually increase to 100%?

after you create the rough mask use the wand to make it nicer, use feather
to soften the edges, you can use a black to clear gradient ON THE MASK itself to graduate the blend

you may have better results using the magnetic lasso for your original selection, it has a bit more control, try it, it’s on a flyout of the lasso
tool.
Why do you convert to greyscale?? why use threshold?

If the mask isn’t what you want, delete it and then make a selection then click the mask icon for a new one based on the selection. don’t clone on your image itself, you can paint or erase on the mask itself
with the paintbrush set to black and white
A
asnowfall
Jun 10, 2006
Today I tried your tips with my new Wacom tablet and I got good results.
When the selection looks good, go to layers palette and click the mask icon.
I did not know it is this easy to make a layer mask out of selection. This tip helped me verymuch.
I made selection using pen & magnetic marquee, conevrt the selection into a Alpha channel and store it for later use. After doing it for some images process of selection does not look time consuming.

Some subjects are hard to make selection of. Example: Tree set against sky.
In these cases I use "Threshold" setting to make the slection.

Thanks
Ramesh

KatWoman wrote:
wrote in message
Sorry for delayed response.
Why do you convert to greyscale?? why use threshold?
I use Gray scale image as starting point for mask generation because mask is gray scale image. I use threshold to generate rough mask. As I said, I am not an expert in Adobe and there may be other better ways to do it.

You wrote..
you can use a black to clear gradient ON THE MASK
itself to graduate the blend
Could you please explain this?
How do I apply gradient on the MASK at the juction of
100% black & 100% white?

BTW: I purchased Wacom Intuos tablet. This should help selection.
Thanks
Ramesh

Assuming this is a color landscape type image
use the magnetic lasso to separate the sky and land, or use Select>color range, clean up the selection using the wand, try various tolerances, add and subtract options of the tool, tick contiguous.
To check the selection click the mask icon in the tool bar, you may wish to touch up with the brush. Once you have a good selection, you may wish to soften using select feather or smooth. Always check the mask edges, making a good mask will not leave the bad matched edges in your final.
When the selection looks good, go to layers palette and click the mask icon. part of it will be white and part of it black. Click on the mask icon to make sure you are working on the mask not the image. Put the colors on default (black & white) choose the gradient tool. If you are working on the black area of the mask use the white to transparent gradient, make sure it’s set on linear, pull the gradient (hold down mouse button and drag) only on the area you wish to effect, the gradient does not have to go over the entire layer.
This should give you a smoother transition area.

I am sorry I didn’ t realize you are working in HDR I think it’s 16 bit? some tools are not available unless you switch mode to 8 bit (I am not too sure about HDR)

KatWoman wrote:
wrote in message
I want to merge two pictures. But my requirements make it not so easy. Most of HDR techniques take whole frame in to account to generate mask. I do not want to that. I use merging for landscape pictures which have sky & land.
I would like to generate mask which seperatessky & land. Mask should have 100% black for sky and 100% white for land.

Let me explain this with an example….
Assume a frame with sky, mountain and lake(with little glare). Glare on the lake may be
nearly as bright as sky, but I would like mask to ignore the glary lake when generating mask.
Final mask should be provide demarkation between sky & land.
Currently I use a crude method to do this.
1) Convert the image to Grayscale

2) Use "Threshold" to generate mask. The threshold value that I use would have a value of the *darkest* cloud near the the horizon.

4) Apply Gaussian blur to above generated mask.
3) Use above generated mask for merging the image.
4) Use the ‘stamp’ tool to polish horizon.

Problems with above method…..
Mask would not be perfect and it leaves hightlights along the horizon. I need to do some ‘cloning’ to correct this.

Another solution….
Can I generate a mask with opacity of 50% near the horizon and gradually increas to 100%?

Please let me know if there are better ways to do this.

Thanks
Ramesh

Note: I am novice in Adobe PS. If you have any idea please give precise ket strokes 🙂

Can I generate a mask with opacity of 50% near the horizon and gradually increase to 100%?

after you create the rough mask use the wand to make it nicer, use feather
to soften the edges, you can use a black to clear gradient ON THE MASK itself to graduate the blend

you may have better results using the magnetic lasso for your original selection, it has a bit more control, try it, it’s on a flyout of the lasso
tool.
Why do you convert to greyscale?? why use threshold?

If the mask isn’t what you want, delete it and then make a selection then click the mask icon for a new one based on the selection. don’t clone on your image itself, you can paint or erase on the mask itself
with the paintbrush set to black and white

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