Occasionally I receive comments about hot spots on the images that I post. On my most recent one the egrets were slightly underexposed out of camera, so I did a curve adjustment in CS5 by holding down the option key and moving my right slider to the left until I saw the beginning of a white spot. Several comments indicated that there were several hot spots.
Q1: Where in CS5 can I go to see the numbers and determine if I have hot spots?
Q2: If I do a curves adjustment and just barely use my sliders until a tiny white spot appears, how can I have too many hot spots?
Q3: When NPN members comment on hot spots, do they determine that there are hot spots by looking at numerical data or just by viewing on their monitor?
I've only been a Photoshop user for about a year, and I have a lot to learn. Thanks in advance for taking the time to give me more insight into this issue.
I can't speak for others, but I suspect some people base their comments on simply viewing the image in their web browser, while other people actually check the image in Photoshop or another application tat shows the histogram.
Simply viewing this image on my Mac in Safari makes me suspect it has hotspots (parts of the image where the RGB values reaches the maximum 255 in at least one of the channels) in the brightest areas on the two closest chicks and on the shoulder of the adult.
Bringing this image into Photoshop where I can view the histogram confirms this - the pixels are still going strong at the right end of the plot showing hotspotting. Checking all three color channels shows R and G burning out with B barely making it under the 255 value.
Another Photoshop tool some of us use is a Threshold adjustment layer. This looks at the luminance of each pixel (think of this as the average of the value for each channel that ranges from 0 to 255): those below the slider value show as black while those above the threshold value show as white. I've included a screen shot of the threshold panel with the slider all the way to the right (value = 255) to show those pixels that are beyond the limit.
Reset the values used by Curves and Levels by double clicking the black and white eyedroppers and enter 20 instead of zero and 245 instead of 255 and see if that helps when you try your adjustments. Never push any adjustment so close to the limit - leave a bit of room for other adjustments. Note that sharpening works by increasing local contrast so if the image is already at the limit adding sharpening can push it beyond the limit.
When you open the Threshold layer, if you move the slider all the way to the right, the layer will be all black unless there are already hot spots. Move the cursor slowly back to the left until white appears (unless white has already appeared with the slider pushed all the way to the right). Click on the white spot with the Color Sampler tool.
Then move the Threshold slider all the way to the left, turning the layer white. Move it slowly to the right and mark the first black spot with the Color Sampler tool.
Now you've marked your brightest highlights and darkest dark areas. You've created two points that appear in PS but won't appear in your final photo.
Open the Info pallet, if you don't already have it open. The Info pallet will show the RGB values for these two places in your photo. These values will change to reflect the changes you make in the photo.
Keep an eye on them while you're processing, especially the highlights. I try to keep the highlights at a max of 250, unless I want to show a part of the photo as being appropriately blown out, such as perhaps the sun.
Hi Dottie: You've already received some great advice. Thought I'd add another possible technique. Rather than using a curves or levels adjustment, try creating a blank layer above the birds, change the blending mode to linear burn (or darken, or multiply - try them all). Paint with a black brush at a low opacity (5-10%) on the brightest offending areas. If it seems too much, lower the opacity of the layer itself. I think you'll be surprised at the amount of detail that you'll be able to retrieve.
Basically, you'll create a new layer at the top of the stack, set it's blending mode to soft light and 50% grey fill. You then use a soft brush to burn/dodge. I use this all the time, and it works very well.
Tony has a free, downloadable PS action that will create the layer for you.
One thing I will point out: If there is no detail in either shadows or highlights, no amount of dodge or burn can put it there. If you're not sure, trying dodge and burn certainly can't hurt. If the area looks drab and lifeless after trying to dodge or burn, there's nothing there that can be rescued.
I agree with all the above comments. I would like to add that it is not necessary to eliminate all hotspots or total black areas. Sometimes we get caught up trying to make technically perfect photos and forget that life gives us areas that are blown out but about which we don't need detail. The most obvious examples that I can think of is when a lit light buld is included in the photo or specular highlights from a chrome surface or the depest shadows under a rock. Normally, we don't expect detail in these areas. As long as it's not important to the overall context and feel of the scene, don't stress. Your birds may have some slight hot areas which would be nice to eliminate, but overall it doesn't bother me. If I were viewing the image enlarged to say, 16x20, it might be more of a problem. But as it is, I'm okay with it.
Dottie you mentioned the egrets were slightly underexposed out of the camera, it looks like that's not the case. If you spot metered your exposure on the brightest spot on the egrets the histogram would indicate that which it doesn't. If proper exposure of the egrets is what you are after than that is all you should be exposing for forget the background. Looks as the egrets have lost detail due to overexposure. Once you have lost it or more accurately "not captured it" there is nothing that can be done it's simply not there.
Discussion
6 repliesOccasionally I receive comments about hot spots on the images that I post. On my most recent one the egrets were slightly underexposed out of camera, so I did a curve adjustment in CS5 by holding down the option key and moving my right slider to the left until I saw the beginning of a white spot. Several comments indicated that there were several hot spots.
Q1: Where in CS5 can I go to see the numbers and determine if I have hot spots?
Q2: If I do a curves adjustment and just barely use my sliders until a tiny white spot appears, how can I have too many hot spots?
Q3: When NPN members comment on hot spots, do they determine that there are hot spots by looking at numerical data or just by viewing on their monitor?
I've only been a Photoshop user for about a year, and I have a lot to learn. Thanks in advance for taking the time to give me more insight into this issue.
Dottie
Simply viewing this image on my Mac in Safari makes me suspect it has hotspots (parts of the image where the RGB values reaches the maximum 255 in at least one of the channels) in the brightest areas on the two closest chicks and on the shoulder of the adult.
Bringing this image into Photoshop where I can view the histogram confirms this - the pixels are still going strong at the right end of the plot showing hotspotting. Checking all three color channels shows R and G burning out with B barely making it under the 255 value.
Another Photoshop tool some of us use is a Threshold adjustment layer. This looks at the luminance of each pixel (think of this as the average of the value for each channel that ranges from 0 to 255): those below the slider value show as black while those above the threshold value show as white. I've included a screen shot of the threshold panel with the slider all the way to the right (value = 255) to show those pixels that are beyond the limit.
Reset the values used by Curves and Levels by double clicking the black and white eyedroppers and enter 20 instead of zero and 245 instead of 255 and see if that helps when you try your adjustments. Never push any adjustment so close to the limit - leave a bit of room for other adjustments. Note that sharpening works by increasing local contrast so if the image is already at the limit adding sharpening can push it beyond the limit.
When you open the Threshold layer, if you move the slider all the way to the right, the layer will be all black unless there are already hot spots. Move the cursor slowly back to the left until white appears (unless white has already appeared with the slider pushed all the way to the right). Click on the white spot with the Color Sampler tool.
Then move the Threshold slider all the way to the left, turning the layer white. Move it slowly to the right and mark the first black spot with the Color Sampler tool.
Now you've marked your brightest highlights and darkest dark areas. You've created two points that appear in PS but won't appear in your final photo.
Open the Info pallet, if you don't already have it open. The Info pallet will show the RGB values for these two places in your photo. These values will change to reflect the changes you make in the photo.
Keep an eye on them while you're processing, especially the highlights. I try to keep the highlights at a max of 250, unless I want to show a part of the photo as being appropriately blown out, such as perhaps the sun.
I hope this helped.
Here is a nice tutorial from Tony Kuyper that shows you how to create and use a Burn/Dodge layer.
Luminosity Painting
Basically, you'll create a new layer at the top of the stack, set it's blending mode to soft light and 50% grey fill. You then use a soft brush to burn/dodge. I use this all the time, and it works very well.
Tony has a free, downloadable PS action that will create the layer for you.
One thing I will point out: If there is no detail in either shadows or highlights, no amount of dodge or burn can put it there. If you're not sure, trying dodge and burn certainly can't hurt. If the area looks drab and lifeless after trying to dodge or burn, there's nothing there that can be rescued.
--P