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IDIOTS GUIDE TO COLOUR MANAGEMENT PART 3 OF 5
CAMERA AND PHOTOSHOP SETTINGS..

Introduction

In this section we will deal with working in Photoshop with your wide gamut aRGB monitor and will consider how best to save images to the web in such a manner that anyone else viewing them stands the best possible chance of seeing them presented correctly. You may have experienced strange colour shift behaviour in "Save for web" and wonder what's going on and we will address that too.

Camera settings

Before I get to Photoshop, just a few words about camera settings. If you shoot RAW as I repeatedly recommend throughout my tutorials, then it doesn't matter whether you define the aRGB colour space at this point or not. RAW does not assign a colour space, you can choose either sRGB or aRGB it doesn't matter. Only when the RAW image is converted is colour management information embeded. This is not the case if you use jpeg. The camera will assign the profile that you set in camera.

Working in Photoshop - settings for aRGB color space

1.0 Color Settings

Photoshop and Lightroom are examples of colour-aware editing software. However, you need to tell them some basic information at the start. For example, in Photoshop, go into Edit >Color settings and set it up as per my own settings below and you will be fine. I have the box marked Profile mismatches when opening files box ticked as this is very useful I find.


2.0 Adobe Camera RAW (ACR) settings

On opening a RAW image in ACR you will see at the bottom of the screen where I have circled below some small but vital text.

Click on this text and another box opens :



The top white box enables you to select Adobe RGB (1998) to be selected from the drop-down list and you should set the Depth to 16 bit. This is best for doing image editing with minimal damage. This setting temporarily doubles the filesize so you will need to remember to convert back to 8 bit in Photoshop later or you will be occupying double the storage space on your computer ! To do this click on Image > mode > 8 bits per channel.
I set resolution to 300ppi as this is the industry standard resolution for printing.
I don't tick the output sharpening box as I will sharpen myself later in Photoshop according to what I am going to do with the image e.g print, output for web etc. The degree os sharpening required varies according to the image size so it is best to do this as the lsat satge in your workflow.

Click OK and you are set. You will convert images into aRGB upon saving or opening.

3.0 Opening images in PS - Profile mismatch warnings

If you only have aRGB images and you have Photoshop and ACR set up as above, then aRGB images will simply open correctly on your aRGB monitor.

However if, like me, you have a mixture of aRGB and sRGB images, when you open an image that is in a different colour space to the current working one, then as long as you have ticked the Profile Mismatches box in Photoshop > Edit > Color Settings, you will get a warning that the document does not match the working colour space. It looks like this:

So, how do we decide what to do ? In the example above, I attempted to open an image that had an sRGB profile embeded, into the Photoshop aRGB colourspace. Photoshop therefore brought up a warning. If you are intending to keep the image as sRGB and perhaps are intending to resize it and upload it to the internet you need to select "Use the embeded profile (instead of the working space) " then click OK. The image will then open in Photoshop correctly as Photoshop has retained the sRGB tag and knows how to handle it to appear correctly.

I don't usually use the "convert the documents colours to the working space" when opening an sRGB image as the image will be upsampled to invent the missing data as it is going from a small to a large colour space. If going the other way from aRGB to sRGB it is less harmful as image data is simply being discarded rather than invented.

I haven't yet found a use for the "Discard embeded profile (Do not color manage)" option.

Opening untagged images.

Finally, the last option that I need to cover is bringing an untagged image e.g. from the web into Photoshop.
I first noticed this issue when I downloaded one of my own images from the internet and saved it onto my computer. When I opened it in Photoshop I did not get a warning and I noticed that it was an untagged image. How did I realise this ?

Well for one, the image was oversaturated and secondly there is a small information box on the bottom left of the Photoshop toolbar that can be changed to profile via clicking the arrow beside it which brings up a drop down list of options.

So this is an easily overlooked situation on some images as there will be no obvious warning as before. So how do we deal with such images ?

If you click Edit > Assign profile or convert to profile you have a range of options open to you.
As the names suggest, if you assign a profile it will only be temporary and the document is not actually changed, however if you convert to Profile you change the image profile permanently. You can of course undo this at any time but it will be destructive.

Just choose your desired course of action as once tagged, all options will look correct in Photoshop as it knows what to do with it.



In part 4, I will cover "Save for web" issues.