RP LIVE "Ask an Adobe Engineer" with Chris Cox

[Doug Nelson]

Although Chris Cox posts regularly in the Adobe support forums, many of you probably have never heard of him. But every single one of you has a favorite Photoshop feature that he is largely responsible for. Sometimes it seems there's not an area of Photoshop that Chris hasn't either written from scratch or vastly improved.

On the next RetouchPRO LIVE, Chris will answer questions from the RetouchPRO LIVE audience. And we'll be watching his desktop live, so he can show examples while he explains how Photoshop works.

Saturday, January 30, 4pm CST (see link below for other time zones)

Click the following link for details and ticket sales:
http://www.retouchpro.com/index.php?page=cox

[Flashtones]

Doug, I don't really have a sense of what this show can do for me. Any more info you can provide?

[Doug Nelson]

It's not going to make you rich or anything. It's more to satisfy curiosity or answer long-held questions about Photoshop. If there's nothing you've ever wondered about Photoshop itself, then it probably can't do much.

I've provided access to the one person on earth that knows more about how Photoshop works than any other. What you do with that person is up to you

[Flashtones]

Don't get me wrong, I know who Chris Cox is and I think it's a surprising and interesting twist to have him on. Kudos for thinking outside the box! I was just wondering if you guys had a bit of an outline, or knew there were certain topics/techniques/practical applications, etc. that were sure to be covered.

[Flashtones]

How at liberty will Chris be to discuss CS5?

[Doug Nelson]

No outline at all, no preset topics. He's agreed to show up and answer audience questions. If the audience doesn't ask any questions, they'll have to listen to him answer mine (I have a lot of them, but they might only be interesting to me).

That being said, the man is fascinating to listen to. Our technical check was scheduled for 10 minutes and ended up lasting over 3 hours. Just knowing that you're learning about how Photoshop works from the man that made it work that way is refreshing. No interpretations or educated guesses, just definitive facts (and some math to back it up if you're not careful).

So if you're not curious about things like why Motion Blur is still bidirectional, what the real difference is between Overlay and Soft Light blend mode, why there are only 4 reliable zoom levels under 100%, etc., then this might not be of interest.

Of course, Chris also works daily with some of the most influential people in the industry, so his views about those areas might prove enlightening.

[Doug Nelson]

Originally Posted by Flashtones

How at liberty will Chris be to discuss CS5?

Honestly, any guess I'd make about this would almost certainly be wrong. But you can ask him yourself

[Flashtones]

Got it Doug. Sounds interesting. Thanks.

[Doug Nelson]

I find myself in the (very good) situation of offering a show of interest far beyond retouching, so please help spread the word to other Photoshop forums.

[mistermonday]

Doug is correct about Chris probably knowing more about how the code behind PS works more than anyone on the planet. While he is not likely to leak much about what's in CS5, this could be an excellent opportunity to ask for new features, especially ones that would make work of a retoucher more effecient. I know I have a long list.
Doug, I will spead the word to a large group of Photoshopaholics & PS technical gurus.
Regards, Murray

[KR1156]

someone please ask him why you cannot delete multiple paths from the "paths" pallet at once, like you can in channels. I had to create a work panel with a script to do this seemingly simple function!!!

[Doug Nelson]

Thanks, Murray. This is a bit of an experiment. My hope is to make this a semi-regular event, both with Chris and with other Adobe personnel. But for that to happen we need to impress upon them that there is significant interest. There's still a day left, but so far the interest is light. Any help at all in getting the word out will increase the chances of making shows like this a regular feature for RP LIVE.

[Doug Nelson]

You might want to write your questions down in advance in a text document so you can simply copy and paste them into the Questions window during the show. Then you can concentrate on the show instead of typing. (please only post one question at a time, though. Not the whole text file in one paste)

[Doug Nelson]

There's still time for you to invite your friends to get their Photoshop geek on with us.

[Doug Nelson]

The ticket sales link will close in 2 hours.

[Doug Nelson]

The ticket sales link will close in 1 hour.

I don't know if a show like this will rebroadcast, so make sure everyone you think might be interested knows about it ASAP.

[Doug Nelson]

The ticket sales link is now closed.

Here's a helpful page if you have audio problems (scroll 2/3 down)

If you haven't received your confirmation email, check your spam folder.

If you can't connect, verify you have Java installed and active.

Come back to this thread after the show and tell us your thoughts about it. Also, give us your requests for future shows with Chris Cox.

[TriniK]

A little - no waaay over my head, and I was hoping to get some of the hard questions asked, and those most discussed/complained about on just about all Photoshop forums, ie why does Photoshop crash (quit unexpectedly... and some). I understand that one has to be polite to one's guests, but I was hoping there was a kind and gentle way of finally getting an answer to this really big problem. It is not a matter of saving one's work either, as frequently it crashes as I am in the process of saving - or trying to, and then it is a gnashing of teeth and back to doing it all over again. When you are working on a tight deadline this is really unacceptable. First webinar that I did not make it through all the way to the end. Great for engineers I am sure, but guess I am just too dumb to have found it riveting. Sigh...

[bakerser]

First, a big thanks to Chris for doing the show. Your knowledge and insight are as valuable as your time.

Second, if Chris agrees to do this again, can we get a private forum or thread for the registrees to post up questions in advance with polling conducted to 'vote' for them to be asked / answered? As well so that Chris can go through and cherry pick some of his own favorites to answer during the session?

Third: One of mine which we didn't have time for. The High Pass filter has a greater contrast to its result than the USM filter, and inability to directly pair it with Gaussian Blur for spatial de+reconstruction. This was presumably done for a brilliant technical reason (much like 15bit 16bit images is brilliant - one will understand in light of the above my appreciation for a true middle gray), but what was that?

[Chris Cox]

TriniK:

We fix all the crashing problems that we know about, and ship dot releases for those that are found after we ship. But we are at the mercy of the Operating system that we run on, and the drivers that we have to use (printers, scanners, sound, graphics, etc.). Third party plugins also run in the same process as Photoshop, and bugs in those plugins can cause Photoshop to crash. And the new GPU/OpenGL features in Photoshop CS4 have exposed us to more driver issues, complicated by the rapid release of new drivers by GPU makers. New releases of Operating Systems can be especially troublesome, as not all the problems in the OS may be worked out (the old "wait for the third service pack" wisdom).

I monitor the Photoshop crash reports that people send in. There are a huge number of third party crashes (drivers, OS and plugins), but not nearly as many Photoshop crash causes as you may think. When we see a pattern to the crashes, we document them and send the details to the responsible party. When it's our fault, we try to fix it. (I've got a few head scratchers that we can't figure out, but I've added extra safety to our code to deal with those situations and try to avoid crashing, while getting us more information about the cause).

Crashing while saving: are you using MacOS 10.6? Yeah, Apple is still working on that. Personally, I'm still running MacOS 10.5.8 : fewer crashes, fewer headaches.

[doctorontop]

Thanks to Chris and Doug I really enjoyed the show

The drop white action would be very useful .........

[Chris Cox]

And here is the "White To Transparency" action.

[Chris Cox]

bakerser - nothing brilliant there. USM and Highpass are related. Highpass does the difference between original image and GBlurred image and adds 128 (or 16384 in 16 bit) and that's it. USM skips the offset, and adds a fraction of the result back to the original image (if we ignore the threshold setting).
Using HighPass for sharpening can get more or less contrast than USM, depending on the blend mode used. That's because you're not just adding the difference but multiplying, screening, etc.

[bakerser]

Originally Posted by Chris Cox

bakerser - nothing brilliant there. USM and Highpass are related. Highpass does the difference between original image and GBlurred image and adds 128 (or 16384 in 16 bit) and that's it. USM skips the offset, and adds a fraction of the result back to the original image (if we ignore the threshold setting).
Using HighPass for sharpening can get more or less contrast than USM, depending on the blend mode used. That's because you're not just adding the difference but multiplying, screening, etc.

First, thanks for the response.

Second, because it is directly calculating the difference, HP as implemented suffers from clipping when the difference between the original and GB version is >0.5 (say a series of hard lines). I've tried for some time to reconcile why that would have been coded (vs. halving the difference, which would reproduce the original image when blended in LL [losing one level to rounding]) and was wondering if there was a scientific reason for this, or if it simply wasn't expected that most would go HP'ing past a few pixels when it was coded?

Edit: Third: Thanks for sharing the action!

[Chris Cox]

Easy: HighPass wasn't planned as a way to sharpen, it was just a high pass filter. Even the blend modes to use it for sharpening weren't invented at the time HighPass was written (Photoshop 1 or 2, can't recall right now).

[TriniK]

Thank you Chris for giving me some insight into the whole "crashing" issue that is the bane of my Photoshop life. (Frankly sometimes I wonder if I have another life...) I imagine that one has to be able to look under the bonnet at the engine which we as laymen are not able to and therefore blame it all on Adobe. '

There will still be a gnashing of teeth as I don't see the problem going away, but at least now I will be more understanding and good to know that the reports are monitored as I was sure they were just being sent into some alternate reality out there.
Thank you.

[mistermonday]

Chris, welcome to RP. I am really sorry I was not able to make the Saturday time slot.
It is wonderful for all of the retouchers and Photoshopaholics hear to have a direct ear into Adobe for new features that will make us all more effective in our work / play and help make PS even more successful than it is.
As for the High Pass filter, I remember it from PS2. Everyone seems to have adopted the filter as the new "in" way of sharpening. However, everyone seems to have ignored the much maligned Unsharp Mask Filter, having been in PS for about as long. It turns out that an "Apply Image" High Pass will produce exactly the same result as the Unsharp Mask Filter with the same Radius setting and the Amount = 100 and Threshold = 0. Except with the USM, you can adjust the sharpness (edge contrast) with the Amount slider as well as adjust the Threshold. So with HP you go through a lot more work to achieve the same, or inferior results.
Anyway, I hope you will come back for another session with RP very soon. And of course if you are ever looking for feedback or beta testers, I am sure you would find a lot of cooperative and eager people here.
Congratulations on the milestone of the 20th anniversary of Photoshop and best wishes on the launch of CS5.
Regards, Murray

[bakerser]

Originally Posted by mistermonday

However, everyone seems to have ignored the much maligned Unsharp Mask Filter, having been in PS for about as long. It turns out that an "Apply Image" High Pass will produce exactly the same result as the Unsharp Mask Filter with the same Radius setting and the Amount = 100 and Threshold = 0. Except with the USM, you can adjust the sharpness (edge contrast) with the Amount slider as well as adjust the Threshold. So with HP you go through a lot more work to achieve the same, or inferior results.

I would argue that by default, the HP filter returns a decidedly inferior result, clipping any differences > 0.5 to 0 or 1 as appropriate and losing the resulting detail. Some cling to it for workflow reasons (sharpening, skin work, smoothing wrinkles, etc), and of course there is the "Dave Hill = High Pass" contingent which will always survive on it. Interestingly, the Legacy B/C adjustment is a surefire solution (-50 contrast) for still using the HP filter in a workflow without suffering the clipping - not sure if that's of interest around these parts, though.

[TriniK]

Just as an aside, and I know that this is not a Photoshop forum so shall post it on one, but during the webinar when I expressed the dislike of the default "tab" opening, Chris said to got to preferences and just uncheck the "open in tabs" box. I did not say anything at the time, but I had already done this before and Photoshop just decided to ignore my request. Well after the webinar I tried it again, and in spite of relaunching Photoshop etc., and the box is clearly unchecked, the documents are still opening in tabs. Let me rephrase that. If I open a document (file >open) then fine - it floats, but if I drag a file from my desktop to the PS interface it jumps right to the tab position and then everything else disappears and I have to go to the icon or to Window >float all in windows, to get my already opened files/images back. That is the part that is driving me a little nuts. Chris if you are still viewing these postings and have any advice or feedback on this I would be eternally in your debt.

[Chris Cox]

Hmm, I've never seen the preference fail EXCEPT when you try to open more than 100 documents (we eventually run out of resources to keep opening system windows and fall back on tabs to keep the number of windows in check).
That limit is lower if you have OpenGL enabled (it uses more resources). But I think it's still around 50 windows or higher.

If that isn't the case, and the preference is turned off -- then I'm not sure why it would still open documents in tabs. I made sure we had the preference because I LOATHE documents in tabs. And on Mac and Windows, I haven't had it fail to work as expected.