Date   

Re: THANK YOU to Color Theory Group and Dan!

Dan Margulis
 

On Sat, Jan 30, 2021 at 05:49 AM, Matthew Croxton wrote:
I want to thank the Color Theory Group members who have financially supported the move to a paid platform and to Dan for his largesse in sharing the abundance of your generosity. I am a high school photography instructor who uses the PPW panel and supporting materials in helping my students learn color and image correction. I'm thrilled to share that because of your thoughtfulness, I now have a dozen copies of Dan's Modern Photoshop Color Workflow (MPCW) to use in the classroom! And use them we will…as soon as they are covered with contact paper to extend their service life. I just received the books today and have already whisked them away to the skilled hands of the school library assistant for this essential order of business. :-) Students will benefit from being able to see the before/after corrections, and will accelerate their learning of image adaptation between screen and print. I think most teachers of Photoshop focus on tools and their applications, but I appreciate the emphasis in MPCW (and here in the Color Theory Group) to dwell instead on identification and speedy correction of deficiencies, handling color and contrast separately.

While it will by no means compete with the corrections I know you will enact in the current Hotel Lobby challenge, I gave the same rules and limitations to my students this week. Here are some of their results: 

Hotel Lobby Challenge: Mr. Croxton's Class

Keep in mind that a few of these students are working from LR mobile or PS mobile and are essentially "pulling parameters" rather than using more advanced actions in desktop PS. The original, unmodified image is the last one in the list, for reference. I find that I learn from seeing their versions more about the objects in the scene, and what colors and tones deserve emphasis. You are welcome to "like" your preferred version in the poll, but I don't think the free account I'm using will support all that many votes.
Thank you again!
Now that the time for new entries in our own study has expired, I've reinstated the link in Matthew's message.

Dan Margulis


Hotel Lobby: Results

Dan Margulis
 

 

I’ve posted the results of the Hotel Lobby exercise, the first in a series of 11 case studies.

 

Reviewing: This image was part of the MIT study. We are asked to assume that this is a promotional image for a certain hotel, showing how tasteful and elegant their interior design is.

 

We have 141 entrants, a record. Most people also submitted a list of their steps, thanks very much. I haven’t read these, because I’d rather get a sense of who was successful and who wasn’t before investigating why. 

 

The files don’t have people’s names on them, and were random-generator numbered from #101 to #141. As with past studies, we also have a “par” version, #142. To get it, I chose what I thought might be the five best entrants, and averaged them, each one weighted 20%. This often creates a version that is superior to most if not all of its parents.

 

I’ll have some things to say about this assortment, but as usual I’d like to open it up to group discussion first. What do you think should and should not be done with an image like this? What do the successful versions have in common? Meanwhile, if you’d like to know how your own version stacked up, download the par version and compare the two directly. Do you think you got the same kind of quality? If not, I hope you’ll find further discussion useful.

 

The Folder is in the group's Photos section, Case Study 2021: Hotel Lobby, 

https://groups.io/g/colortheory/album?id=259709

 

I also have zipped all 42 files and uploaded a 61 mb file to our Files section,

https://groups.io/g/colortheory/files/

Search for 020121_Hotel-Lobby_entries.zip

If you are going to study these versions I strongly encourage you to download these files. Many of these entrants vary only in a minor way and it is hard to see the impact of a change without toggling back and forth between them.

 

I look forward to your comments.

 

Dan Margulis

 

P.S. Our next case study will be announced today, look for a separate post.


moderated Re: Case Study Announcement: Hotel Lobby

Dan Margulis
 


On Jan 29, 2021, at 6:29 AM, Dan Margulis via groups.io <dmargulis@...> wrote:

Since there are more than a dozen entries already, I’ll post now, and then again Sunday morning.

OK, this is the final confirmation before posting. If you submitted an entry before 06:00 eastern time today, you should find your initials here. The deadline for receipt of others is 06:00 easters/1100Z/12:00 ora italiana tomorrow.

I confirm receipt of entries from the following individuals:

BB
EB
GB
ReB
RoB
KC
MC
HD
JaG
RG*
HH
KH
BI
SJ
PM
SN
JP
DR
DS
JS
KS
RT
LV
FY
CZ

*indicates that a corrected version was submitted

Entries from the following were at an incorrect size/cropping and would have to be resubmitted:

JC

Dan Margulis


moderated Re: Case Study Announcement: Hotel Lobby

Dan Margulis
 



On Jan 30, 2021, at 9:52 AM, k_d@... wrote:

Dan,

Can you comment on Hotel Lobby submissions: what would be your max. file size expected .jpg, so we can assess our submissions to not exceed file size submitted?...and to avoid too large files in future?

When next entries (next weeks, different images) are due, can you estimate max. file size to submit; so we can check before we submit?

There’s no way to give exact file sizes because, among other things everybody uses different levels of sharpening, which is difficult to compress in JPEG methodology and results in larger sizes.  Therefore it wouldn’t do to examine the files sizes of the unsharpened default versions because it wouldn’t be surprising if our own work took up two or even three times as much space.

And that is the case here. The defaults are around 850k. All of our versions are larger, typically around 1.2mb with one as high as 2.5.

File storage is cheap. Nevertheless we do have certain limitations, which is why we work on files that are smaller than the MIT retouchers had. I don’t see why we need higher resolutions for the purpose of this group and I don’t see the need to save files that take up ten times as much space as the defaults.

Dan


moderated Re: Case Study Announcement: Hotel Lobby

Doug Schafer
 

Dan,

Can you comment on Hotel Lobby submissions: what would be your max. file size expected .jpg, so we can assess our submissions to not exceed file size submitted?...and to avoid too large files in future?

When next entries (next weeks, different images) are due, can you estimate max. file size to submit; so we can check before we submit?

Doug Schafer


moderated Re: Case Study Announcement: Hotel Lobby

Dan Margulis
 



On Jan 29, 2021, at 6:29 AM, Dan Margulis via groups.io <dmargulis@...> wrote:

During these case studies entries have been known to go astray, or to be submitted at the wrong size etc. Therefore my practice has been to post a herd confirmation roughly 48 hours ahead of time, so that if there is a problem with your entry, or it wasn’t received by me, there’s time to make amends. Since there are more than a dozen entries already, I’ll post now, and then again Sunday morning.

Make that Saturday morning, because an unreasonable number (four) of entries have come in with an incorrect format. I have fixed three and the fourth has been resubmitted correctly, so no further action is required. I request, however, that more attention be paid to these details. The issues so far:

1) file size reduced by e-mail client, requiring that I contact the sender to get a full-size copy.

2) file size at 2832x4256 rather than 2000x3006.

3) file submitted in Adobe RGB rather than sRGB.

4) file submitted in ProPhoto RGB and saved as JPEG level 12, resulting in a filesize three times as large as anyone else's.

A reminder that entries are due in this case study in about 48 hours, at 06:00 eastern time Monday/1100Z/12:00 ora italiana

I confirm receipt of entries from the following individuals:

BB
EB
GB
ReB
RoB
KC
MC
HD
JaG
RG*
HH
KH
BI
PM
JP
DS
JS
KS
LV
FY

*indicates that a corrected version was submitted

Entries from the following were at an incorrect size/cropping and would have to be resubmitted:

None

Dan Margulis


THANK YOU to Color Theory Group and Dan!

Matthew Croxton
 
Edited

I want to thank the Color Theory Group members who have financially supported the move to a paid platform and to Dan for his largesse in sharing the abundance of your generosity. I am a high school photography instructor who uses the PPW panel and supporting materials in helping my students learn color and image correction. I'm thrilled to share that because of your thoughtfulness, I now have a dozen copies of Dan's Modern Photoshop Color Workflow (MPCW) to use in the classroom! And use them we will…as soon as they are covered with contact paper to extend their service life. I just received the books today and have already whisked them away to the skilled hands of the school library assistant for this essential order of business. :-) Students will benefit from being able to see the before/after corrections, and will accelerate their learning of image adaptation between screen and print. I think most teachers of Photoshop focus on tools and their applications, but I appreciate the emphasis in MPCW (and here in the Color Theory Group) to dwell instead on identification and speedy correction of deficiencies, handling color and contrast separately.

While it will by no means compete with the corrections I know you will enact in the current Hotel Lobby challenge, I gave the same rules and limitations to my students this week. Here are some of their results: 

Hotel Lobby Challenge: Mr. Croxton's Class

Keep in mind that a few of these students are working from LR mobile or PS mobile and are essentially "pulling parameters" rather than using more advanced actions in desktop PS. The original, unmodified image is the last one in the list, for reference. I find that I learn from seeing their versions more about the objects in the scene, and what colors and tones deserve emphasis. You are welcome to "like" your preferred version in the poll, but I don't think the free account I'm using will support all that many votes.
Thank you again!

~Matt Croxton


moderated Re: Case Study Announcement: Hotel Lobby

Dan Margulis
 



On Jan 24, 2021, at 7:23 AM, Dan Margulis via groups.io <dmargulis@...> wrote:

We launch our series of ten case studies, with an eleventh optional one. This one, sort of a warmup, is one of the two easiest of the 11, IMHO.
 
During these case studies entries have been known to go astray, or to be submitted at the wrong size etc. Therefore my practice has been to post a herd confirmation roughly 48 hours ahead of time, so that if there is a problem with your entry, or it wasn’t received by me, there’s time to make amends. Since there are more than a dozen entries already, I’ll post now, and then again Sunday morning.

A reminder that entries are due in this case study in about 72 hours, at 06:00 eastern time Monday/1100Z/12:00 ora italiana

I confirm receipt of entries from the following individuals as of 06:00 eastern time this morning:

BB
GB
RB
KC
MC
HD
JaG
RG*
PM
JP
DS
KS
LV

*indicates that a corrected version was submitted

Entries from the following were at an incorrect size/cropping and would have to be resubmitted:

None!


Dan Margulis


FW: Case Study Announcement: Hotel Lobby

Robert S Baldassano
 

 

 

From: Robert Baldassano <robsbchat@...>
Sent: Tuesday, January 26, 2021 12:53 PM
To: colortheory@groups.io
Subject: Re: Case Study Announcement: Hotel Lobby

 

I double checked my entry already submitted and it is 2000 x 3006. When I started I just opened it directly in PS.

 

Sent from Mail for Windows 10

 


Re: How does Luminance slider in Camera Raw split colors by their hue? #colortheory #photoshop #lightroom #colors

Doug Schafer
 

On Tue, Jan 26, 2021 at 06:12 AM, Dan Margulis wrote:
Does anybody know how those ranges are calculated?
My thought process (in no way disagrees with Dan).....
Suggest you run your own tests. You won't get the math answer and I doubt Adobe would ever release the info (proprietary), but you will have a mathematical relationship result.

Create a full spectrum rainbow color wheel or similar; or just larger than the range of colors you expect to test...then save/look at several results on the colors of moving 1 slider, a specific amount, and analyze  (i.e. color sample eye dropper the results) and tabulate a chart of the results vs. the changes made; and draw your own conclusions.

I would guess the range is not a specific color number set (RGB or Lab), except to start at the exact Hue, 100% away from the center for some amount, and then  a gradient taper from that color to the next with a specific color number cutoff at an end point where there is no effect on image being adjusted.  I think the result will be of a somewhat flattened "normal curve" with the peak at Hue = 0 (for "red") extending partly to Hue = 60 for yellow and partly to Hue = 240 for blue  (for RGB) with slider effects of no impact before yellow or blue. Where the colors cutoff (i.e. the range you are looking for) will be measurable by the color picker and will probably vary by the amount the slider is moved.

If you do so, most here would appreciate your results summary. Once done for 1 color, I'd likely assume a similar scheme is used for each color....unless visual interpretation is used....like Dan said: a difference of science vs. illogical; thus the "normal curve" may not be symmetrical and could be different for each color.

Doug Schafer


Re: How does Luminance slider in Camera Raw split colors by their hue? #colortheory #photoshop #lightroom #colors

John
 

First off, thank you for your answers! For sure you know way more about colors than me.

Just to clarify my objective a bit - I'm working on a photo editor software and I'm trying to implement color controls which would look familiar to a Lightroom/Photoshop user.
I've got the basics working, but can't figure out which color model to use.

For the images processed in the software I start with RGB and I've tried converting to HSL, HSV & CIE Lab. For each model I allow the user to change the values that make up the color model then convert it back to RGB for displaying on the screen in real-time.

The issue I have is setting the "intervals" affected for a certain color. For ex. for red #FF0000 I tried converting it to HSL and tried to consider reds the colors with a close hue value (I know it's wrong). I've also tried using some vector math to determine the distance between various colors in the image to "clump" them together around red.

I'm not really getting good results, aside from the CIE Lab model - however, that gives me a few aberrations and unexpected overlaps of colors.

So probably the right question to ask would be which is a good algorithm to determine color similarity?

thanks!


Re: How does Luminance slider in Camera Raw split colors by their hue? #colortheory #photoshop #lightroom #colors

Kenneth Harris
 

If you want to puzzle this out, you can use a granger rainbow to see which clean colors are affected.  A long time ago (PS7) I worked out which areas were selected by H/S for each color using calculations.  I don't have my notes in front of me, but IIRC, H/S is colorspace agnostic, it's just ratios, and it corresponds to the peak  angle + rolloff in the old HSV/HSL colorspaces.  Again IIRC, conversion into HSV via the plugin is also colorspace agnostic.  Further, if you take a granger rainbow, and add a Z dimension of saturation, H/S will continue to affect the same ratios.  For instance, run each range in H/S to zero and any images, and it should be greyscale.  Although now I use the logic of how selective color cuts the image apart regularly (via an action), I've totally forgotten what is is, although again, it can be emulated via calculations.  Selective color doesn't cut deeply into unsaturated areas.  If you put selective color to zero on all the blacks, and set to "absolute," the image will turn to white, you can then move and individual range up and see if you you're catching what you want for the purpose of masking, eg, "reds.".  I did not come up with this method, perhaps someone here can attribute, it was circa 2005.  

I have tested how ACR handles it, but I know the hit on peak response is much higher, and the rolloff to low response faster while the range is broader, for a given color.  My sense is that it's still looking at RGB equivalent ratios even though ACR should be in a CIE space.  I'll happily be disabused of my ignorance.

Combining these methods, it's possible to go from a particular/known colorspace into a space that looks ~95% like Lab using only calculations, that is, if you know what kind of reds you want, and what kind of greens you want, ditto yellows/blues, you can get a/b.  The L is trivial.  I could never get the reds perfect, however, too dark.  A granger rainbow was invaluable in testing all that.

Ken Harris


Re: How does Luminance slider in Camera Raw split colors by their hue? #colortheory #photoshop #lightroom #colors

Dan Margulis
 



On Jan 20, 2021, at 8:39 AM, John <johnny.php@...> wrote:

the HSL panel in Camera Raw allows adjusting Luminance for 8 color ranges I assume.

 

Does anybody know how those ranges are calculated?

 

For ex. what does "Reds" actually mean, how does it determine what is red and not orange for ex.

it's clear that RGB or other color space values are in play here, but how does the math actually work.


John,

The flip, or wisecracking, response to the question is,

1) Probably nobody remembers what methodology was used. The Photoshop team often has picked up pieces of existing code to create new commands. Also there are several complicating factors in a command like this that might require some less than desirable shortcuts.

2) It is hard to see what good knowing this information would do. There are good reasons to have an exact knowledge of what curves or white balance do, or what constitutes “red” in sRGB as opposed to Adobe RGB as opposed to ProPhoto. But the nature of this particular command is that it can only be used in a by-guess-and-by-gosh way where we twiddle the sliders and try certain settings, and if we don’t like the particular way in which the affected area is computed we make a better mask ourselves.

The realistic response is:
If we are designing this command from scratch there are two basic approaches:

1) Do it in a logical mathematical way that will appeal to color scientists.

2) Do it in an illogical way with the idea that a slider labeled “Reds” will affect only areas that a non-color scientist might consider red.

These two approaches cannot be reconciled. Assuming that you have decided to select areas that the average person might consider red or blue or yellow, the size of the selection covered by each couldn’t possibly be the same. Yellow, for example, is only perceived as yellow in very light tones, whereas blues are recognized as blues in a range three times as large.

Assuming that you could somehow pinpoint the exact color that the average person considers red or blue or yellow, the selection areas would also not be symmetrical. The irregularities have been known for some time. In his 1858 On Colour John Gardner Wilkinson complained, 

I have stated that the names of colours are uncertain and indefinite, and in proof of this it is only necessary to ask what idea is conveyed to the mind by the mere mention of a red, or a blue, color? A scarlet coat is called red; and the term red is applied to a rose, a brick, port wine, mulberries, cherries, and other things of very different hues…

If you force people to pick one color and call it red, they’re probably going to choose something in the neighborhood of scarlet. So a command targeting “Reds” has to be strongest in that zone. In a command designed for color scientists, the selection would tail off equally on both sides. However, in real life we can’t go much in the yellow direction before declaring that the resulting color is orange and not red. All the objects above cited by Wilkinson are on the other side—we still consider things to be red when they have moved sharply toward magenta.

With blues it’s the same idea. If we have a basic agreement on what blue means we will accept quite a large hue shift before we call it aqua. But if the shift is in the other direction it won’t take much for us to call the color purple.

That ad hoc approach is the one I would take if I were designing the command.

Dan Margulis 

P.S. Welcome to the list. We request that everyone posting use their full name. We suggest editing your groups.io profile so that your full name appears in the message header.


moderated Re: Case Study Announcement: Hotel Lobby

Paco
 

Posted just as a heads up. In PS it can be downsized without any problem an it matches the jpegs perfectly.

Paco


moderated Re: Case Study Announcement: Hotel Lobby

Ronny Light
 

I opened the file, Hotel Lobby a3500-default.jpg, into Photoshop, through Dropbox, without resizing, and the file in Photoshop is 2000 x 3006 pixels, just as Dan said.

 

 

Ronny

www.RonnyLightPhoto.com

5010 B Wilkerson Dr., Nashville, TN 37211

 

 

 

From: colortheory@groups.io <colortheory@groups.io> On Behalf Of Kenneth Harris
Sent: Monday, 25 January, 2021 12:36 PM
To: colortheory@groups.io
Subject: Re: [colortheory] Case Study Announcement: Hotel Lobby

 

I've tried ON1, Iridient, Affinity, and Camera Raw, and they all seem to think it's 12mpx, 2832x4235.   It's shot on a Nikon D700, that's the spec.
Ken Harris

_._,_._,_

 


moderated Re: Case Study Announcement: Hotel Lobby

Ronny Light
 

In Bridge—I don’t use Lightroom—you can open an image in Photoshop at its size or choose to resize.

 

 

Ronny

www.RonnyLightPhoto.com

5010 B Wilkerson Dr., Nashville, TN 37211

 

 

 

From: colortheory@groups.io <colortheory@groups.io> On Behalf Of Gerald Bakker
Sent: Monday, 25 January, 2021 2:20 PM
To: colortheory@groups.io
Subject: Re: [colortheory] Case Study Announcement: Hotel Lobby

 

On Mon, Jan 25, 2021 at 08:51 PM, Dan Margulis wrote:

Last time, we may recall, certain people were acquiring the image in the wrong dimensions because Lightroom (I think it was Lightroom) was applying some kind of lens correction that distorted the size. I forget the solution, but there was one.

I bet the solution is to switch off any lens corrections that may have been applied automatically (as configured in a lens profile), or manually.
For an automatic correction, switching off the "Enable Profile Corrections" checkbutton in the Lens Correction panel may do the trick.
--
Gerald Bakker
http://geraldbakker.nl

_._,_._,_

 


moderated Re: Case Study Announcement: Hotel Lobby

Gerald Bakker
 

On Mon, Jan 25, 2021 at 08:51 PM, Dan Margulis wrote:
Last time, we may recall, certain people were acquiring the image in the wrong dimensions because Lightroom (I think it was Lightroom) was applying some kind of lens correction that distorted the size. I forget the solution, but there was one.
I bet the solution is to switch off any lens corrections that may have been applied automatically (as configured in a lens profile), or manually.
For an automatic correction, switching off the "Enable Profile Corrections" checkbutton in the Lens Correction panel may do the trick.
--
Gerald Bakker
http://geraldbakker.nl


moderated Re: Case Study Announcement: Hotel Lobby

Dan Margulis
 



On Jan 25, 2021, at 1:48 PM, Kenneth Harris <reg@...> wrote:

Pardon, 2832x4256.  FileViewer also agrees.  
Ken Harris

OK, that solves half the mystery, but there’s more.

When this was originally given to the MIT group the size was indeed 2832x4256. I know this for a fact because I participated and opened the same .dng that they did.

For the purpose of this group, I wanted a smaller filesize, so I specified 2000x3006, which is the same aspect. When I re-opened the .dng in Camera Raw to make the default versions, I just typed in 2000 px short direction and got the same result.

Anyone who has a size of 2832x4256, all you have to do is Image: Image Size, choose Resample and Constrain Proportions, and type in 2000.

Last time, we may recall, certain people were acquiring the image in the wrong dimensions because Lightroom (I think it was Lightroom) was applying some kind of lens correction that distorted the size. I forget the solution, but there was one. Therefore, since that time I’ve put a notice in the case study announcement that people need to check their acquisition size against the default if there is any doubt.

Since Ken has 2832x4256 he’s out of the woods. BUT:

Paco reports 2832x4248, without saying in what module.

Then, in view of Ken saying he opened it at a different size in Affinity, I moved the .dng over to where I have that application. And before I tried to open it, from the Finder I did a File Info. Hallelujah! 2832x4256 just like I hoped.

But, as the devil would have it, five seconds later Affinity opened it as 2844 x 4284. That would reduce to 2000x3012.6. When I forced it anamorphically to 2000x3006, it was pretty close, but not close enough for blending into a par.

So apparently there is some hocus-pocus going on by default that needs to be corrected. The suspect is a lens correction, but everybody’s system is likely different. I don’t know what else to say except be careful.

Thanks for these reports.

Dan





moderated Re: Case Study Announcement: Hotel Lobby

Kenneth Harris
 

Pardon, 2832x4256.  FileViewer also agrees.  
Ken Harris


moderated Re: Case Study Announcement: Hotel Lobby

Kenneth Harris
 

I've tried ON1, Iridient, Affinity, and Camera Raw, and they all seem to think it's 12mpx, 2832x4235.   It's shot on a Nikon D700, that's the spec.
Ken Harris

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