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Colour Profiles and viewing on monitors


powerlord

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Hi chaps,

A while ago I catibrated all my monitors with my Spyder 5 (https://spyderx.datacolor.com/)

A bit like monitor speakers (which I use for recording music), this is maybe not how you would want to actually use a monitor like all the time - since it's purpose is really to standardise colours, and aid professional print, video and photography. It creates a very deep profile where the smallest change from absolute black is determinable, etc.

After hearing others on the forum, this seemed like a good idea as a basis for editing my Astro pics.

However I'm now, not so sure.

Here's an example - and a bit like trying to demo different sound quality and youtube, there will have to be some compromises to try to demo colour profiles on here so it's viewable on everybody's monitor (and really that's the crux of the matter).

Here's M27 - 30 mins of data shot last night. The first picture is as edited by me on my calibrated monitor. On that calibrated monitor I see lots of Oiii clouds out to the sides of the dumbbell.

However, if you are viewing this on a non-calibrated monitor, as most of you will be (stuff generally just looks better with deeper backs, more compression), you probably don't see them.

m27s.thumb.jpg.f11336244e7058f565a698b5e3f61dcd.jpg

 

To try to demonstrate what you see on a calibrated monitor, I took a pic on my phone of the screen - this kinda worked. ignore the blown out highlights - which are not blown out on the monitor, and note the shadow portions - this is what I see - all that oiii cloud billowing out:

 

example.jpg.8a3e18f0df612c80eed4e645874dd39a.jpg\

 

So my question is really, IF the audience of a photo is to be on the internet, on a forum such as this, it seems to me posting 'properly' calibrated and edited photos is maybe not correct ? Would I be better creating and edited version which I create while setting my monitor to a more regular 'out the box reduced colour gamut' that is more representative of what most people have ?

If I do that, I get something like this (this was done quickly and could be better - but basically I've applied a curve to the lower end shadows, pulling them up into visibility on such a profile:

m27reducedgamut.thumb.jpg.4a9b6ccd6562ce21a40f590803f19049.jpg

Obviously doing so, necessarily compresses the colour gamut - so there's less depth in the core - but if you are viewing this on your phone/tablet or a 'regular' monitor you CAN now probably see those outer Oiii clouds.

Opinions ?

stu

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I can see the fainter parts fine with both of my monitors (and phone), the blown up version looks like it had a bit too much stretch, true. Maybe a compromise between the very dark first image and the third one would work best? My primary display is has a factory set sRGB mode, which i have not tested nor probably will bother to since i think it looks great. My secondary monitor is a cheaper one with no such setting and it looks fine on that too, but i never use the secondary monitor for actual processing because it has a very slightly different output of colours. In my opinion an image that has the right colours will look good in any monitor, but just better in the better monitor.

What i will say about the visibility of the fainter stuff here is that the image is quite oversampled and would benefit from binning, especially for these faint areas where the noise grain has started to come up due to too much stretch.

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13 minutes ago, powerlord said:

So my question is really, IF the audience of a photo is to be on the internet, on a forum such as this, it seems to me posting 'properly' calibrated and edited photos is maybe not correct ? Would I be better creating and edited version which I create while setting my monitor to a more regular 'out the box reduced colour gamut' that is more representative of what most people have ?

Think of calibration as "conforming measuring device to a standard".

Imagine we have rulers but they all have slightly different scale. Some of us have a ruler that is close to metric standard, some of us have ruler that is further from metric standard.

Now you post your measurement of a cube and say - this cube has side of 23.4mm.

What would you rather do - measure it with ruler that is calibrated against metric standard so that what you've written is actually correct, or would you accept that your ruler is slightly off and you are posting wrong measurement - justification being that most of other peoples rulers are skewed in some way and no one will correctly verify your measurement?

In my view - just because other people don't calibrate their screens - is no justification not to do it yourself if you have the gear for it.

However - you should be careful and understand color management and why we calibrate screens - in order to do it properly.

There are two primary reasons why we calibrate our computer screens:

1. to make things uniform across viewing devices

2. to make viewing device / screen match actual physical color / light and our perception

First part is much more important to artists and teams working together - but if done on its own (without other part) - can lead to "wrong" results

Bottom line - in order to properly utilize color calibration of your screen - make sure that you keep environmental conditions the same and calibrate against those (I see a lot of difference in same image depending on whether I'm viewing it in daylight or in dark room at night) and make sure you do proper color profile / color space management when editing your images.

Make sure to convert to sRGB color space when saving an image as that is standard color space on internet at the moment.

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If you can see the fainter bits, then yeh the 3rd will look too stretched.

But for those who can't, the 3rd will look 'normal'. I suppose that's what I'm getting at.

Oh no doubt it's over sampled - it's asi2600 shot with a 300p (0.5x0.5")!

But none of that changes the gamut issue tbh. The fact remains I'd be interested in how many people can clearly see the outer clouds in the first image. My feeling is there is maybe, as you say a bit of compromise necessary for those of us using calibrated monitors if we want all the darker bits - whether its dark nebula or dust, etc be visible to most viewers ? While keeping our own 'fully gamut' version for ourselves or printing, etc ?

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1 minute ago, DaveS said:

I have a calibrated wide-gamut monitor and see the outer shells just fine.

Well, you will do.  that's my point.

Sorry if I'm not being clear.

IF you have a calibrated monitor, 1 will look great - all shells clear.

IF you don't, and your monitor is more 'typically' setup - it will crush blacks - that's the usual sort of profile. And you'll find it difficult to see the outer shells.

 

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In fact - here is interesting little exercise for anyone interested.

It does not involve calibrated screens - so it can be performed by anyone.

Process and image during daytime with daylight in your room. Remember how you processed it and save image somewhere.

In the evening / night - make your room dimly lit or maybe remove all light sources except computer screen (like when watching a movie / theater experience) and try to process same data to the same level as you remember it (don't look at your previous processing yet). Once you are done - save that one as well.

Now make two comparisons - one in daylight and one at night time with same conditions as you used when processing.

You will find that your images are:

1) quite different

2) one looks good in daylight while other is rather poor, and similarly other is looking good at night, while first one is poor (night time processing will be understretched in daytime conditions and daytime processing will be over exposed in night time conditions).

Above goes to show that if you work in different conditions - you need to calibrate your screen for each of those conditions and apply profiles depending on actual condition at that time.

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6 minutes ago, vlaiv said:

Think of calibration as "conforming measuring device to a standard".

Imagine we have rulers but they all have slightly different scale. Some of us have a ruler that is close to metric standard, some of us have ruler that is further from metric standard.

Now you post your measurement of a cube and say - this cube has side of 23.4mm.

What would you rather do - measure it with ruler that is calibrated against metric standard so that what you've written is actually correct, or would you accept that your ruler is slightly off and you are posting wrong measurement - justification being that most of other peoples rulers are skewed in some way and no one will correctly verify your measurement?

In my view - just because other people don't calibrate their screens - is no justification not to do it yourself if you have the gear for it.

 

 

Now, you see I don't think it's as simple as that. Your analogy is valid, but a bad one imho.

A better one is my monitor speakers. They are great for editing and mixing music as they have a flat frequency response, and so I can make a mix which I know will sound similar on other music creators monitor speakers.

However, the vast majority of music listens do not list on monitor speakers - so we edit music to be more flat on there (to sound bright/lacking bass) - you would NOT want to listen to music on monitor speakers.

However the music will then tend to sound good on a regular joe blogs speaker setup.

I believe the same is the case here - I should probably edit my pictures not to look good on my monitor (similarly to how I edit music to not sound good on my monitor speakers - but be flat) so that it will be good on regular speakers.

Editing on a calibrated monitor is slightly analogous to editing video in a Log format ?

stu

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11 minutes ago, powerlord said:

Editing on a calibrated monitor is slightly analogous to editing video in a Log format ?

I would not put it like that as I don't see analogy.

If you want to use audio equipment and draw analogy there for calibration - analogy that I'd be happy with goes like this:

Imagine you have a violin player, regular set of speakers and monitor speakers in one room and you are sitting in that room blind folded.

Calibration in this case is sound equalizer placed before monitor speakers and regular speakers (two different equalizers, one for each set of speakers - by the way - it just occurred to me why they are called equalizers in the first place :D ).

If calibration is proper, then you would not be able to tell which one is playing - violin player, or recording of them played on either set of speakers. Say they are chosen randomly to play for a minute - you would not be able to tell as sound would be identical regardless of who is playing.

Similarly with computer screens - you have two different manufacturers, so two different devices - and a painting. Properly calibrated screens should present same color / hue and same intensity as painting itself - light emitted (or reflected in case of painting) - should be of same intensity and same spectral response (not spectrum, but same spectral response in our eyes).

That is the point of calibration - to make things uniform / the same, and also to make it same as original source (this bit also has additional component of how original source was recorded - so we need to calibrate recording device as well and that is what conforming to a standard does).

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37 minutes ago, vlaiv said:

 

That is the point of calibration - to make things uniform / the same, and also to make it same as original source (this bit also has additional component of how original source was recorded - so we need to calibrate recording device as well and that is what conforming to a standard does).

yup it is. true.

no argument there.

as Dave just proved - that works well - me, you dave - all see the same thing.

However it doesn't help those who have a more 'regular' monitor. unless we calibrate to that 'standard' - but of course there is none other than my general experience that indicate lots of folk don't. I suppose just like music, that's their fault. But call me a popularist, but I'd like to be able to post my pics to look the way i want them to for those too.

I think I might try starting to post 2 versions - one for calibrate viewing (the correct one if you like), and one compressed to look good on mobile devices and more regular pcs.. see how that goes down.

I find I already to that for sending pics to family on whatsapp, etc as mobile devices nearly aways have this compressed profile.

I would say, that for those with calibrated monitors who comment/critique a user's photos - it may be worth bearing in mind that the creator may not have a calibrated monitor. You may suggest they have over stretched an image for example, but you are not considering that to them, they see a perfectly stretched one.

And of course vice versa.

Short of mandating we all have the same standard calibrated monitors, it is always going to be a factor when considering dark sections I think. Colour - less so - as I think most modern monitors respond reasonably unless the user has made the profile massively warm or cool ?

I think it might explain why sometimes I've seen someone comment on a photo (not necessarily mine) with a stretching comment (too much, not enough), and I've thought -huh.. looks ok to me. Just one of those things I suppose.

stu

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9 minutes ago, powerlord said:

Short of mandating we all have the same standard calibrated monitors, it is always going to be a factor when considering dark sections I think. Colour - less so - as I think most modern monitors respond reasonably unless the user has made the profile massively warm or cool ?

Thing is - it is much easier to calibrate monitor for gamma and black / white without any aid.

You have a bunch of websites that allow you to do it and OSs have inbuilt helpers for this as well.

I don't think it is good idea to produce another version for those that don't have calibrated screens - because you simply don't know in which way their calibration is skewd

Odds are that it won't look good on majority of screens that are not calibrated in the way you intended.

Do try that experiment with processing data in different conditions.

 

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Just now, vlaiv said:

Thing is - it is much easier to calibrate monitor for gamma and black / white without any aid.

You have a bunch of websites that allow you to do it and OSs have inbuilt helpers for this as well.

I don't think it is good idea to produce another version for those that don't have calibrated screens - because you simply don't know in which way their calibration is skewd

Odds are that it won't look good on majority of screens that are not calibrated in the way you intended.

Do try that experiment with processing data in different conditions.

 

yeh, it is available, (e.g.  easly on macos), but doesn't mean folk do it.

A high proportion of viewers of forums such as this will be on mobile or tablet devices that have no easy way to calibrate and very definately are NOT calibrated in such a way that uncompressed blacks show. I'm pretty confident that there is general sort of profile there.

this article sums it up well

https://blogs.scientificamerican.com/symbiartic/how-to-calibrate-your-monitor/

Unless I've chosen the wrong standard to calibrate too (very possible) I've ended up with a gamma more like 1.8 - that washed out look that it correct says allows you to see all sahdes of black.

And as it also says, most users are on a gamma of 2.2 - which compresses blacks more. to quote:

"

If you create mostly images that will be viewed on screen – for the web, PowerPoint, video games, etc. – set your gamma to 2.2. This will help ensure that your images look consistent across the widest range of computers used in business and the mass consumer market.

On the other hand, if you still create most of your work for print (as I do), stick with 1.8. Not only is this setting more compatible with high-end printing system, it also produces noticeably lighter images on screen. This helps you see detail in shadows, something that is critical when creating and editing digital images."

I believe I have calibrated very much to the later. I'll run up DisplayCAL again - maybe I've just been calibrating to the wrong standard ?

 

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Contrast of the display used for viewing the image is up to the viewer to see to but i dont think there is a set in stone right way you can try to please everyone by stretching just the right way.

RE: Colour: I have had many monitors over the years and most of them display colour differently and really only the higher end ones with sRGB built in do a good job. This is something that can be "objectified" by calibration of both the image and display, whereas the contrast issue IMO is not (because most dont care, some view in daylight, some in darkness etc). Photometric colour calibration of the image takes the issue out of my hands and most importantly my eyes.

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I am not an imager and I have an out of the box (uncalibrated) monitor.
Image 2 is showing more outer cloud than image 1 on my monitor for sure.
But I'd still describe image 1 as better than image 2 - the sky is blacker and the stars sharper.

I'm now wanting to calibrate my monitor... but how will films look after calibration?..... do the streaming sites provide footage that looks "best" on "out of the box" monitors?  So maybe for a non imager like me "out of the box" is the place to stay?

 

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yeh imho films look rubbish with a calibrated monitor. But you can have multiple profiles easily enough and swap between them. Or you might find you like it fine.

It's a pity somone like FLO don't offer a library to borrow a calibration device cheaply - they are not inexpensive devices and once you've used it. it just sits on a shelf.

stu

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8 minutes ago, powerlord said:

once you've used it. it just sits on a shelf.

and from the article you quoted above:

"All monitors change over time, so calibration must be done on a regular basis. Most experts recommend doing it every few weeks to every few months."

If you're fussy once you're probably fussy often.  🤔

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6 hours ago, powerlord said:

Unless I've chosen the wrong standard to calibrate too (very possible) I've ended up with a gamma more like 1.8 - that washed out look that it correct says allows you to see all sahdes of black.

And as it also says, most users are on a gamma of 2.2 - which compresses blacks more. to quote:

"

If you create mostly images that will be viewed on screen – for the web, PowerPoint, video games, etc. – set your gamma to 2.2. This will help ensure that your images look consistent across the widest range of computers used in business and the mass consumer market.

Ok, so here is red flag for me.

You don't get to choose gamma. Sure you do - if you consider calibration to be tweaking rather than calibration.

It is not arbitrary process, it is meant to ensure same output for same input (input being digital values of recorded image).

Gamma is meant to ensure perceptual uniformity.

Sensors that record light values (images) are more or less linear - but are much more linear than human vision. Human vision responds much like most sensory perception in humans (pressure / touch, temperature, sound, etc ...) it is logarithmic / power law in its nature.

In another words - we perceive something being twice as bright as something else - it does not mean it's values are twice as high numerically (twice the number of photons) but rather its magnitude (log scale) has increased linearly.

sRGB standard dictates that numeric values correspond to physical brightness with gamma of 2.2 (roughly, gamma function for sRGB is defined slightly differently and is only approximated with gamma of 2.2).

This means that if sRGB pixel values in the image for one pixel are say 10 and for other are 20 - this does not mean that luminosity (emitted photon count) of screen pixel is twice that of first pixel - but rather should be gamma 2.2 corrected.

You can't arbitrarily use gamma of 1.8 if you want to adhere to the standard.

That is why I mentioned two points in above post about calibration. If you only want to get consistency across several of your screens and don't care about rest of the world - calibrate your screens to same values and pick those values as you please, but if you want to follow the standard - make sure you use standard values for calibration.

If you set your screen to gamma 1.8 and then go on and create image that is uniform transition from black to white - and you use your own eyes to ensure that transition is uniform, and save such image. It will no longer be uniform on any computer screen that is even remotely calibrated (at factory).

To show what I mean - here is gamma 1, gamma 2.2 and gamma 1.8 uniform transition from black to white:

image.png.c348136cfb1ff41411c570d49092d23a.png

If you observe above image on regular computer screen - bottom gradient should look most natural, linear and uniform.

If you calibrated your screen for gamma of 1.8 then middle image will look that way on your screen

Gamma 1 won't look right on any screen - but this is how sensor sees the image, and if you take photometer and measure pixel values - they should end up being linear (if viewed on gamma 2.2 screen).

Now thing is - only gamma 2.2 RGB values are in fact going to be linear values - as system expect image values to be gamma 2.2 encoded as that is standard. Look what sort of graphs I get when I plot above 3 images:

image.png.57f6753c495cf0b3a3aff6c4571d29ea.png

Black is gamma 2.2, red is gamma 1.8 and blue is gamma 1.0

What should be linear in values - is actually pretty curved, 1.8 gamma is a bit less curved - and gamma 2.2 values are in fact - linear.

Why? Because system is already expecting values to be encoded with gamma 2.2

Choosing to calibrate at gamma 1.8 - messes with already well established system - where pixel values are expected to be gamma encoded and drivers for computer screen are treating them as encoded and are presenting them with proper pixel intensities so that our brain sees them as linear (although intensities measure by photometer or sensor are not linear).

It is no wonder your processed images don't look good on other display screens if you processed them on system which forces gamma of 1.8 although expected gamma is 2.2

@powerlord

Out of interest, which gradient in above image looks the most linear to you?

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