Topics

Ghost power lines


James Gray
 

I just encountered something peculiar in using the velvet hammer.  The image I was working on had annoying power lines right across the shot of a church.  Before I started the PPW, I created a duplicate layer and used content aware fill to "erase" the power lines.  It worked well with no noticeable artifacts.  Then I started going through the steps of the PPW without flattening.  Because I did not view the image at 100% until after the MMM+CB I did not notice the very light ghost of the power lines until then.  Because I had saved snapshots of several of the steps, I was able to go back and find the step that created the ghost power lines.  It was the Velvet Hammer.  Specifically the darkening function in the VH was the cause.  The mask on the darkening function layer had the dark power lines in it.  That caused the pixels near the power lines to darken but not the pixels where the power lines were, creating the ghost power lines.  Apparently the mask was created from the background layer instead of the composite layer immediately under the VH layer group.

James Gray 


Hector Davila
 

I would have 'first' used the Velvet Hammer, the Lesser Hammer, the Bigger Hammer, *any* Hammer BEFORE i mess around with any related 'conter-aware' removing tools.

You don't remove something then throw a hammer on it...it has to be the other way around.

Then...at the end, if needed it...then you can add a hammer. But as a finishing touch...but even a finishing touch with a velvet hammer will be all over the place.

Hector Davila


Gerald Bakker
 

This is indeed easily reproducible. A workaround is of course to first manually create a composite layer and then apply Velvet Hammer. Or alternatively, use the VH action from the PPW actions (not from the panel), as this works differently and doesn't show this behavior.

My guess is that James's situation is a rare occurrence where this problem actually shows up. I think the answer should not be "Velvet Hammer is supposed to be applied before any retouching work". This may in general be a preferable processing order (is it?), but actions should work correctly no matter the underlying layer structure.

Whether it's worth fixing is up to Dan and Giuliana.

Gerald Bakker
http://geraldbakker.nl


Dan Margulis
 


James Gray writes,


I just encountered something peculiar in using the velvet hammer.  The image I was working on had annoying power lines right across the shot of a church.  Before I started the PPW, I created a duplicate layer and used content aware fill to "erase" the power lines..  It worked well with no noticeable artifacts. 

Temporarily. As a rule retouching should be put off as long as possible because artifacts that are invisible at present often become visible after sharpening, say, or something like the MMM action or other procedure to add tonal and hue contrast to the affected area.

Then I started going through the steps of the PPW without flattening. 

This is a questionable procedure. If convinced that the wires have been correctly eliminated then the original should be discarded or saved as a variant, since you foresee no possible use for the unretouched version.

Because I did not view the image at 100% until after the MMM+CB I did not notice the very light ghost of the power lines until then.  Because I had saved snapshots of several of the steps, I was able to go back and find the step that created the ghost power lines.  It was the Velvet Hammer.  Specifically the darkening function in the VH was the cause.  The mask on the darkening function layer had the dark power lines in it.  That caused the pixels near the power lines to darken but not the pixels where the power lines were, creating the ghost power lines.  Apparently the mask was created from the background layer instead of the composite layer immediately under the VH layer group.

PPW actions are developed for single-layer files. Some will run on multiple layers but this is at the user’s own risk, so extra caution needs to be taken. This particular example sounds like a once-in-a-lifetime deal, where retouching is done prematurely yet the original defect remains in the file. When there are multiple layers it would be possible to configure the action to operate on a merged version, but this would be wrong much of the time and correct much of the time. The script cannot read the user’s mind. We’ve added the Variants function for safety in situations like this.

Dan Margulis 


Dennis Dunbar
 

It sounds like the issue is less about what hammer was thrown when than whether the power lines were completely removed in the first place. 

As an experienced retoucher I’ve seen many times when issues like not completely gone power lines are not easy to see, but there none the less. One good practice is to use various Curves that exaggerate the tones in the image to check for such issues. 

Here is a link to an article I wrote a couple of years ago for SLR Lounge on the idea: http://bit.ly/2jvfihi

HTH

Dennis Dunbar
310-463-1677

Blog: http://dunbardigital.com/blog/

Website: http://www.dunbardigital.com

Twitter: http://twitter.com/DennisDunbar

Co-Author - Photoshop Restoration & Retouching - 4th Edition


James Gray
 

JG(new):  Thanks for the comments.

JG:  I created a duplicate layer and used content aware fill to "erase" the power lines..  It worked well with no noticeable artifacts. 

DM:  Temporarily. As a rule retouching should be put off as long as possible because artifacts that are invisible at present often become visible after sharpening, say, or something like the MMM action or other procedure to add tonal and hue contrast to the affected area.

JG(new):  I understand that as a general rule.  However, I have found that when stacking variants that re-doing the content aware fill on the variants does not blend well in many cases.  I have also recently acquired noise reduction software that works far better on an image that is straight out of ACR than on images that have been through the PPW. 

JG:  Then I started going through the steps of the PPW without flattening. 

DM:  This is a questionable procedure. If convinced that the wires have been correctly eliminated then the original should be discarded or saved as a variant, since you foresee no possible use for the unretouched version.

JG(new):  Clearly it was a bad procedure.  I hoped that describing the steps would help others.  I will not make that mistake again.  Many photographers I interact with avoid flattening as long as possible.  I have no friends in my local community who is willing to try to the PPW.  Since they never change color space it rarely causes a problem.  

JG:  Because I did not view the image at 100% until after the MMM+CB I did not notice the very light ghost of the power lines until then.  Because I had saved snapshots of several of the steps, I was able to go back and find the step that created the ghost power lines.  It was the Velvet Hammer.  Specifically the darkening function in the VH was the cause.  The mask on the darkening function layer had the dark power lines in it.  That caused the pixels near the power lines to darken but not the pixels where the power lines were, creating the ghost power lines.  Apparently the mask was created from the background layer instead of the composite layer immediately under the VH layer group.

DM:  PPW actions are developed for single-layer files. Some will run on multiple layers but this is at the user’s own risk, so extra caution needs to be taken. This particular example sounds like a once-in-a-lifetime deal, where retouching is done prematurely yet the original defect remains in the file. When there are multiple layers it would be possible to configure the action to operate on a merged version, but this would be wrong much of the time and correct much of the time. The script cannot read the user’s mind. We’ve added the Variants function for safety in situations like this.

JG(new):  Yes, it clearly was a risk.  I thought it interesting to report.  Hopefully it helps somebody else.  It was not difficult to fix the problem.  I thought it might be interesting know how the VH created ghost power lines.  The Variants function is a very nice addition, for a lot more reasons than situations like this.  


James Gray
 

Gerald,
Thanks for replying.  I do not think the issue is worth fixing.  Leaving the un-fixed version as the background should be viewed as a mistake.  I also agree with the implication in your reply that general rules about order of processing should not be viewed as absolute.  It is an empirical question as to what works and does not work well.  I also understand for many professional retouchers that they do not have time to test alternatives and they are better off following rules that usually work.

James Gray

On Sat, Sep 7, 2019 at 6:29 PM gc.bakker@... [COLORTHEORY] <COLORTHEORY@...> wrote:
 

This is indeed easily reproducible. A workaround is of course to first manually create a composite layer and then apply Velvet Hammer. Or alternatively, use the VH action from the PPW actions (not from the panel), as this works differently and doesn't show this behavior.

My guess is that James's situation is a rare occurrence where this problem actually shows up. I think the answer should not be "Velvet Hammer is supposed to be applied before any retouching work". This may in general be a preferable processing order (is it?), but actions should work correctly no matter the underlying layer structure.

Whether it's worth fixing is up to Dan and Giuliana.

Gerald Bakker


Dan Margulis
 


Dennis writes,

As an experienced retoucher I’ve seen many times when issues like not completely gone power lines are not easy to see, but there none the less. One good practice is to use various Curves that exaggerate the tones in the image to check for such issues. 

Here is a link to an article I wrote a couple of years ago for SLR Lounge on the idea: http://bit.ly/2jvfihi

An excellent point, to which could be added:

We all agree that retouching is best done late in the process to avoid the risk of artifacts being brought out later that weren’t initially visible.

But we (presumably) all agree that circumstances may dictate that we have to retouch earlier than we would like.

If we must retouch early, and the retouch is pretty easy, like removing wires, then a good insurance policy is to do it two or three times quickly and blend the results. Each time with create potential artifacts but they won’t be identical, so blending them will tone each down and reduce the possibility that any one of them may become obnoxious later.

Dan Margulis



James Gray
 

Dennis,
I think you are mistaken about the power lines not being completely removed in the first place.  You could easily replicate the issue as Gerald Bakker has done.  The original power lines were dark against a light sky.  The ghost power lines were lighter than the sky.  The ghost power lines totally disappeared when I turned off the mask on the darken layer.  It was that simple.  Your general point is well taken as it sometime happens that imperfections in an image are sometimes not completely removed.
James Gray


On Sun, Sep 8, 2019 at 6:30 PM Dennis Dunbar dennis@... [COLORTHEORY] <COLORTHEORY@...> wrote:
 

It sounds like the issue is less about what hammer was thrown when than whether the power lines were completely removed in the first place. 


As an experienced retoucher I’ve seen many times when issues like not completely gone power lines are not easy to see, but there none the less. One good practice is to use various Curves that exaggerate the tones in the image to check for such issues. 

Here is a link to an article I wrote a couple of years ago for SLR Lounge on the idea: http://bit.ly/2jvfihi

HTH

Dennis Dunbar
310-463-1677



Stephen Marsh
 

Hi Dennis,

Thanks for posting the link to the article.

List members may remember the old Binuscan Photoretouch Pro software from around the year 2001?, which had the "bX-ray" feature...

I have posted an archive to the group's Files section titled "Solarization-Curve.zip" (created by Conny Wallström and downloaded from the Retouching Academy website back in 2014).


Stephen Marsh




---In COLORTHEORY@..., <dennis@...> wrote :

One good practice is to use various Curves that exaggerate the tones in the image to check for such issues. 

Here is a link to an article I wrote a couple of years ago for SLR Lounge on the idea: http://bit.ly/2jvfihi

HTH

Dennis Dunbar



Dennis Dunbar
 

Stephen, 

Glad you found the article helpful. Solarization Curves have been used to check work since the early 90’s when the Paintbox users demanded a solution to issues they had trouble seeing on their big Barco monitors. (Big in those days was 25”!)

There are lots of times when even though we look closely we just can’t see issues like the ghosts of power lines, or dust spots on sensors etc that are in the image. When your reputation relies on delivering a clean file your clients can run with it becomes imperative to double check for such issues. 

Back in the early days I learned the hard way when I had to pay $400 for a new set of separations for a Roger Corman movie poster I worked on. When Photoshop first came out with layers there would occasionally be an issue where the edges of a layer (with a layer mask) would leave a 1 pixel edge showing if you rotated the layer. I discovered this when the Marketing VP for Roger brought a poster sized proof to my studio and pointed to a line and said “What’s that?”

Dennis Dunbar
310-463-1677

Blog: http://dunbardigital.com/blog/

Website: http://www.dunbardigital.com

Twitter: http://twitter.com/DennisDunbar

Co-Author - Photoshop Restoration & Retouching - 4th Edition


>>>I have posted an archive to the group's Files section titled "Solarization-Curve.zip" (created by Conny Wallström and downloaded from the Retouching Academy website back in 2014). 

Stephen Marsh 

---In COLORTHEORY@..., <dennis@...> wrote : 


One good practice is to use various Curves that exaggerate the tones in the image to check for such issues. 


Here is a link to an article I wrote a couple of years ago for SLR Lounge on the idea: http://bit.ly/2jvfihihttp://bit.ly/2jvfihi 


HTH 


Dennis Dunbar <<<


Kevin Stecyk
 

Here's a link to a YouTube that describes an efficient method to eliminate powerlines: YouTube



It's the second example in the YouTube.


Best regards, 
Kevin


On Sunday, September 8, 2019, 08:43:45 PM MDT, James Gray James@... [COLORTHEORY] wrote:


 

Gerald,
Thanks for replying.  I do not think the issue is worth fixing.  Leaving the un-fixed version as the background should be viewed as a mistake.  I also agree with the implication in your reply that general rules about order of processing should not be viewed as absolute.  It is an empirical question as to what works and does not work well.  I also understand for many professional retouchers that they do not have time to test alternatives and they are better off following rules that usually work.

James Gray

On Sat, Sep 7, 2019 at 6:29 PM gc.bakker@... [COLORTHEORY] <COLORTHEORY@...> wrote:
 

This is indeed easily reproducible. A workaround is of course to first manually create a composite layer and then apply Velvet Hammer. Or alternatively, use the VH action from the PPW actions (not from the panel), as this works differently and doesn't show this behavior.

My guess is that James's situation is a rare occurrence where this problem actually shows up. I think the answer should not be "Velvet Hammer is supposed to be applied before any retouching work". This may in general be a preferable processing order (is it?), but actions should work correctly no matter the underlying layer structure.

Whether it's worth fixing is up to Dan and Giuliana.

Gerald Bakker