Color Proof - Difference between Monitor Proof and no Proof

"If I select the ICC profile which the monitor calibration software has created as the workspace, the image looks different as when I choose the same ICC profile as a soft proof profile and turn soft proof on. WHY?"

That's because in the first case, you are actually turning off color management altogether. It means document profile and monitor profile are the same, so nothing happens, no conversion, no color management. You've killed the whole thing. You need this conversion. You need both profiles, each in their proper place.

Document and monitor profile serve different purposes, don't mix them up! They are not interchangeable. You need both.

In the second case, the document profile is not replaced, so color management still works. Think of proof as inserting a third profile between the original two. If all links here are straight conversions, the basic appearance remains unchanged. But the proof profile in between acts as a bottleneck the data have to go through. So if you have any gamut clipping in this proof profile, you see that clipping on screen.

In other words, it's a preview of what happens when the final conversion is done in the print process.

But again, I need to stress that you don't do anything with the profile made by the calibrator. It's automatically set up at system level, and that's where it belongs. Photoshop uses it on the fly, without any intervention from you, in a normal profile conversion as you work.

I am editing most images for iOS devices.

In that case you should set sRGB as your Working RGB space and assign it to your images—the RGB Policy should be Preserve Embedded Profile.

Normally you would not work in or assign the system monitor profile. Photoshop automatically converts the assigned color space into the system’s monitor profile for display. Obviously CMYK color can’t be displayed, so there is a conversion i.e., GRACol>Lab>MonitorRGB. Same goes for RGB editing spaces AdobeRGB>Lab>Monitor.

but with a windows image viewer, irfanview or other tools,

They are not color managed.

Normally the purpose of Proof Setup and Proof Colors is to soft proof an output device—the Proof Setup would be set to the output class RGB or CMYK profile for the device you want to soft proof (which would never be your monitor profile). With Proof Colors you can see the preview and get the output numbers without actually making the conversion from your preferred RGB editing space.

Proof Colors is very helpful when the final destination is an offset press. So here I have a relatively large gamut RGB profile assigned as the RGB editing space (AdobeRGB), and I’m proofing to the intended output device—a CMYK press running to the GRACol standard. The title bar shows GRACol as the proof, and the appearance of the color displays in the GRACol CMYK space without actually converting the RGB color. The color bars on the right are out-of-gamut:

In short - don't do anything! Leave it alone. Run the calibration software, done. That's it.

Hi

do I have to select the calibrated color profile in "Color Settings" under RGB ? No the monitor profile is set in the operating system, nowhere else.

Let's say I have selected my new calibrated profile under Color Settings for the RGB working environment - Never do that - the monitor profile describes your monitor. It is not a document space

See if this helps:

Colour Management simple explanation

Digital images are made up of numbers. In RGB mode, each pixel has a number representing Red, a number representing Green and a Number representing Blue. The problem comes in that different devices can be sent those same numbers but will show different colours. To see a demonstration of this, walk into your local T.V. shop and look at the different coloured pictures – all from the same material.

To ensure the output device is showing the correct colours then a colour management system needs to know two things.

1. What colours do the numbers in the document represent? 
This is the job of the document profile which describes the exact colour to be shown when Red=255 and what colour of white is meant when Red=255, Green = 255 and Blue =255. It also describes how the intermediate values move from 0 through to 255 – known as the tone response curve (or sometimes “gamma”).
Examples of colour spaces are (Adobe RGB1998, sRGB IEC61966-2.1)
With the information from the document profile, the colour management system knows what colour is actually represented by the pixel values in the document.

2. What colour will be displayed on the printer/monitor if it is sent certain pixel values?
   This is the job of the monitor/printer&paper profile. It should describe exactly what colours the device is capable of showing and, how the device will respond when sent certain values.
   So with a monitor profile that is built to represent the specific monitor (or a printer profile built to represent the specific printer, ink and paper combination) then the colour management system can predict exactly what colours will be shown if it sends specific pixel values to that device.
   
   So armed with those two profiles, the colour management system will convert the numbers in the document to the numbers that must be sent to the device in order that the correct colours are displayed.
   
   

So what can go wrong :

1. The colours look different in Photoshop, which is colour managed, to the colours in a different application which is not colour managed.
   This is not actually fault, but it is a commonly raised issue. It is the colour managed version which is correct – the none colour managed application is just sending the document RGB numbers to the output device regardless without any conversion regardless of what they represent in the document and the way they will be displayed on the output device.
   
   
2. The colour settings are changed in Photoshop without understanding what they are for.
   This results in the wrong profiles being used and therefore the wrong conversions and the wrong colours.
   If Photoshop is set to Preserve embedded profiles – it will use the colour profile within the document.
   
   
3. The profile for the output device is incorrect.
   The profile should represent the behaviour of the device exactly. If the wrong profile is used it will not. Equally if the settings on the device are changed in comparison to those settings when the profile was made, then the profile can no longer describe the behaviour of the device. Two examples would be using a printer profile designed for one paper, with a different paper. A second example would be using a monitor profile but changing the colour/contrast etc settings on the monitor.
   The monitor profile is set in the operating system (in Windows 10 that is under Settings>System>Display >Advanced) which leads to a potential further issue. Operating system updates can sometimes load a different monitor profile, or a broken profile, which no longer represents the actual monitor.

Colour management is simple to use provided the document profile is correct, always save or export with an embedded profile, and the monitor/printer profile is correct. All the math is done in the background.

I hope that helps

Dave

Dave