Asian Centre, UBC. What's with the haloes?

[waha]

I shot this image mainly because I wanted to try out HDR. Now I'm noticing a halo effect where the trees meet the sky. How could I have fixed this, or --better yet-- how could I have avoided it in the first place?

Feel free to share your wisdom on this topic or any other observation you might have about the image.

Thanks,
waha

[FrankMi]

Hi Wayne, halos are a common issue with tonemapped images, more so at the skyline but they may appear elsewhere in the image as well. In this case you have a cloudless sky so you may be able to easily blend back in some of the original image to minimize the effect. Depending upon what software you are using for the HDR processing, you may have some options in the way of adjustments that can minimize the halos. If you find that the tonemapped image really helps areas other than the skyline, you can also go the other way and blend the parts of the image that benefit from the tonemapping back into the original and avoid the halos altogether.

If the image is critical and you can't get sufficient joy out of the previous approaches, there are some labor-intensive techniques that can be applied as well. If you have to go that far you want to ask yourself if you really need to process the image with HDR techniques.

Tonemapping also tends to:
1. make the sky and clouds unrealistically dark
2. give skin tones a 'sickly' appearance, and
3. give foliage a vibrant, almost 'electric' appearance
as a result, there is often recovery that needs to be done afterward, usually by blending back in some of the original image.

HDR processing techniques can produce some fantastic results that are not achievable any other way (at present), but you may need to be willing to invest some learning time and processing effort to get those results.

[waha]

Thanks, Frank, but...but...
I've just started to experiment with HDR (via Photomatix), and I wonder if you could take a minute to elaborate on the meaning of blending "the parts of the image that benefit from the tonemapping back into the original and avoid the halos altogether." You sound like someone well-versed in the mysteries of HDR. Are we talking about selecting part of the HDR image and then using one of the blending modes to "reunite " it with the original? Am I on the right track here?

Maybe the explanation would be too involved, in which case I would settle for just a hint...if you care to give it.

Thank you for your attention.

waha

[FrankMi]

Hi Wayne, I'll need to respond to your question tomorrow as I am out of time tonight, but it involves using layers and masking in post processing. I am also using Photomatix but for post processing, I use Photoshop CS5. Any post processing software that does masking an layers can be used to do the blending. If you are using Photoshop or Elements, I can be fairly specific on the process but if you are using something else I'll only be able to provide the general processing steps. Let me know what PP software you are using and I'll try to get back to you tomorrow! In the meantime, take a look at StuckinCustoms.com and look at Trey Ratcliff's free HDR/Photomatix tutorial as he can also show you how to blend the output of Photomatix with the original image. Cheers!

[Dave Humphries]

Hi Wayne,

I'm afraid the shot here has nothing in it which warrants the use of HDR techniques - there is nothing here that was beyond the range of almost any camera sensor to record if properly exposed, so why 'mess with reality' tone mapping with Photomatrix and suffer these artefacts?

Straight forward PP from RAW would achieve a realistic result, which seems to be what you are after (well done for that )

HDR is a technique for producing an image of a scene which contained tonal values exceeding say 12 stops, the sort of thing might be a say an architectural or automobile picture with chrome in with a reflection of the sun in, plus the sunlit building/car and requiring unlit shadow detail to also be clearly visible. i.e. one with a light source in shot, which you want to see detail of, as well as detail in shadows. Your shot above (nice though it is) just doesn't fit that criteria, it is just a reflected light shot with a dynamic range of a few stops only.

Now, if you were after the 'ultra tone mapped' look that many mistakenly call HDR, then sure, it can be tried on any image, but usually a cloudy sky is a prerequisite.

I guess I am asking "what did you expect Photomatrix to do for you with this?"

Hope that helps,

[FrankMi]

OK Wayne, I was out all day and am just getting back. I realize that the image you have (as Dave points out) may not be ideal for HDR but if you are trying to learn how to use the tools, I'm still happy to show you what I know. I didn't notice any info on what post processing software you are using or whether or not you were able to find what you needed at StuckinCustoms.com or elsewhere. I guess I'll need to wait to hear from you.

When I started to learn HDR I started by taking indoor pictures. The shadows inside the house to the light coming in the windows provided all the contrast I needed to practice with Photomatix. You may want to give that a try. Here is the first one I tried to do.



This one was Tonemapped from 5 images at -4EV, -2EV, 0EV, +2EV, and +4EV. I was able to recover everything from the dark wall to the left of the hutch through to the bright sunlit scene outside the window but as you can see, there there are a lot of unresolved issues, the most obvious of which is around the windows.

This is one of my more recent HDR images.

[waha]

Frank,

Thank you so much for your offer to share your knowledge. I've been slow to respond to your question because of an intervening emergency. So, yes, I am using Photoshop Elements with Photomatix. Tomorrow I will take a look at StuckinCustoms, but would still appreciate your help with masking/layers/blending if you can find the time.

waha

[waha]

Dave,

Your point is, of course, well taken.
When I took the picture of the Asian Centre, I was suffering from itchy shutter-finger syndrome, which drove me irresistibly to fire off the three shots required for my newly acquired HDR toy. And yes, I was only dimly aware that HDR does not improve every picture, and that includes the one I submitted here. So thank you for making that clear. I shall keep your advice in mind.

waha

[Dave Humphries]

Dave,

Your point is, of course, well taken.

Oh dear, have I overdone it again? sorry, I'll just climb down off this soapbox

That's better

[SpiderBob]

Frank,

Thank you so much for your offer to share your knowledge.....but would still appreciate your help with masking/layers/blending if you can find the time.

waha

I always look for the topics on this subject, I certainly would pay close attention.

[FrankMi]

would still appreciate your help with masking/layers/blending if you can find the time.

Hi Wayne and Bob!

Update: After I finished this tutorial I was searching for links for Elements techniques and found that the ability to create masks the way I describe below is only available with Elements 9 and later, There are links, however on how to simulate masks in the earlier versions of Elements. I'll post the links at the end of the tutorial as I research them.

I’m going to assume that you haven’t used Layers and Masking as yet in Adobe Elements and as I have Photoshop CS5 and have been told that Masking and layers in Elements is ‘the same’, I am hoping that any differences will be minor.

Let’s start with Layers. When you open an image, it creates the full image in the main window and a locked ‘Background’ thumbnail of the image in the Layers Panel.



Although you can unlock the Background layer, for now, let’s make a copy to play with by using the Layer menu/Duplicate Layer. When you make a change to a layer it can be ‘undone’ using Edit/Undo but if you’ve done a lot of changes, you may not want to undo them all to get back to a specific change. There is a better way and that is to, in effect, place a clear plastic sheet over the image and draw to your heart’s content knowing that you can erase what is on the plastic sheet and the underlying image hasn’t been modified. We can do this by using Layer/New Layer.



We can use the Brush Tool from the Tools Menu to draw changes on the new layer. Because we see through the new transparent layer to the copy of our image, it looks like we are changing the image. We can also click on the new layer in the layers panel and right-mouse click and select Delete Layer if we want to get rid of the new layer.

Let’s move on to Photomatix. You know how to add multiple exposure copies of an image to Photomatix to produce a tonemapped image similar to the one at the start of this thread. I’m not sure if Bridge is available in Elements, but in Photoshop you can open Bridge and select multiple images. We want to select the three original copies AND the tonemapped output JPG image from Photomatix, and open them with Tools/Photoshop/Load files into Photoshop Layers.

If Bridge is not available in Elements, you should be able to open the tonemapped image in Elements and copy/paste each of the three original images into the tonemapped image as layers.
1. Drag the image to the main screen.
2. Click the check mark to accept.
3. This creates a new Layer.
4. The layer is entered as a Smart Object.

To convert each Smart Object layer to a raster image so that we can modify it, right-click the layer thumbnail and select ‘Rasterize Layer’



We could now make changes to any of the Multiple Layers (except Background). The only layer we can SEE in the main screen is the TOP layer that has the ‘EYE’ (see the tip of pointer for # 3 above). We can remove the ‘eye’ symbol and see the layer below it by clicking it on or off. Let’s turn off the ‘Eye’ for the top two layers so we can see the third layer.

The only layer we can CHANGE is the one that is SELECTED (blue). We can select multiple layers but not all features work with multiple layers selected and some features only work with multiple layers selected. Click on the gray area of the thumbnail to select the layer. For now let’s select the Third layer, the one that is displayed in the main window (if you turned the Eye off for the first two layers).

Here is a handy feature. Select all of the layer thumbnails and choose Edit/Auto-Align Layers and Projection = Auto to align the layers in case the images don’t align perfectly as shot. Very helpful if you didn’t use a tripod!

It’s time to see what Masking can do. Masking is like cutting a hole in one of the layers to see what is in the layer below. In our example, if we cut a hole in the third layer that is the size, shape and location of the basket on the table, we would see the much lighter basket from the fourth layer through the hole. We do this by adding a Mask. To add our Mask, select the third layer thumbnail and use Layer/Layer Mask/Reveal All.

You should now see a white ‘mask’ beside the thumbnail image. Here is how the mask works. Anything on the mask that is white displays the corresponding area on this layer. Anything that is black shows the corresponding area on the layer below as if a hole had been cut in the image of this layer.



We want to use the mouse to click on the thumbnail 'mask', rather than the thumbnail 'image', and use the brush in the main image to paint holes in the mask where we want to see what is below. If we make a mistake we can either Edit/Undo, or, simply paint over the mistake with white instead of black!

Anything that is a shade of gray blends the image from this layer with the one below. The darker the Gray, the more the image below is seen and the less this image is seen. Simple, but very effective!

So Blending is simply painting on the mask to reveal what is below by using a shade of gray rather than pure white or pure black. This can be done several ways. You can paint using a shade of gray but a more effective method is to use the Opacity setting of the brush to control how much gray you want to use. You can also select different brush styles and control how soft or hard the brush blends by using the brushes Hardness setting. When the Opacity is set to less than 100%, multiple brush strokes increase the effect. As you paint on the main screen, you’ll see the changes taking place in both the main image and the thumbnail mask. Remember to select the active layer’s Mask before you paint with the brush or you may find that you have painted on the actual image!

In the image above I used a black brush to paint through the mask to reveal the brighter basket in the layer below, then changed the opacity of the brush to 50% and painted the table top which resulted in a blending of the mask (third) layer with the forth layer below.

The last step would be to save the result as a JPG or Print. If I wanted to be able to come back to the layers, I would save the image as a PSD (Photoshop) file that will preserve the layers but would take up more hard drive space. To save hard drive space I could merge some or all the layers back into a single layer using Layer/Merge layers.

For blending, I would normally make the Photomatix tonemapped image the top one and blend in each of the layers below as appropriate to pick out specific lighter or darker areas that may contain the detail I am trying to include in the final image. Likewise, if I only wanted to blend a little bit of the tonemapped image, I would place the normally exposed image layer at the top of the stack and again just blend in the pieces of the tonemapped image that I wanted.

To go further with masking and layers, you may want to learn about making Selections which can be used to make more sophisticated masks. Not only can selections be used to create masks but masks can be used to create selections. Masks can be transferred between layers, which helps when you want to mask through multiple layers as in the example below.

In this example there are four different areas of the image that can be adjusted separately from each other, the foreground, the island, the background, and the sky. Each area has its own mask and the combination of the white on each mask produces the complete image.



I hope this makes sense! Please let me know if you have any questions!

Update: It looks like the easiest workaround to not having basic Masks in earlier versions of Elements is to use the mask that come with the Adjustment Layers. Adjustment Layers are fantastic! They allow you to add multiple adjustment controls (Brightness, Contrast, Curves, Levels, etc.) to any layer and change any of them on the fly. They also have their own built in masks. So the answer appears to be, add an Adjustment Layer to the second Image layer, don't bother making any adjustments if you don't want to, link the first layer (Layer/Create Clipping Mask) to the Adjustment Layer for the Image Layer below it and simply use the mask. By the way, the last image above is using multiple Adjustment Layers and you can see the masks in use.

Links:

http://www.photoshopessentials.com/b...ke-layer-mask/
http://graphicssoft.about.com/od/pse...ermasktool.htm
http://help.adobe.com/en_US/Photosho...3d59-7f88.html
http://www.alibony.com/pse/020708layer-mask.html
http://www.youtube.com/watch?v=jIhkWvAwjZo

[SpiderBob]

I for one thank you for taking the time to write this up. It is much appreciated.

Bob

[waha]

Frank,

Oy veh, oy veh. So much to learn, and so little time! (I'm 71 years young).

Thank you so much for your tutorial. To use a well-worn phrase, you have gone "above and beyond the call of duty." I almost feel guilty for causing you all this work with one single question. You have cleared up a number of foggy spots for me, but if more fog moves in during future readings, I will let you know.

waha

[FrankMi]

LOL! No problem, Wayne. Give it a go and let us know what questions come up. Cheers!