Major Project: Post-Production: Colour Grading Footage

Colour grading Footage

As previously mentioned in my 'Adapting to Premiere' post, I am still getting to grips with Adobe Premiere. Now that I've finished the fine cut and have the structure for the narrative confirmed with little to change, I've decided now would be the best time to begin colour grading. With previous experience with Final Cut Pro, I know that there are several ways of going to colour grade. Therefore, I begun to research on Lynda to see which technique seemed to be the best.

As I've been connected using Lynda since I begun my degree at university, I knew this would be the best site to choose for my research. Nonetheless I eventually came across a colour correction guide using the Lumetri colour toolset, which can be seen from the link below:

http://www.lynda.com/Premiere-Pro-tutorials/Following-proper-color-correction-workflow-using-Lumetri-color-toolset/371692/414027-4.html

Below are the key aspects I've learnt on colour correcting in the recommend manor:

Understanding the types of Luma scopes

 Before I begin, it is essential to explain how colour correction can pursue by using a range of different graphs that are used to make it easier to see what exactly you are changing in an image (in terms of colour). These graphs which are all introduced in the video are listed as shown in the image below:

Vectorscope YUV & Luma Waveform Scopes

Nonetheless, the video first begins by explaining how altering both the black and white levels can help get the corrected image you want. This is done by using either the Vectorscope YUV graph, or the waveform (Luma) graph, which will both be explained. As you can see in the image below which shows the graph in its Vectorscope YUV format, you can use the graph on the right hand side which enables you to manually alter your four key colours in an image - white, red, green and blue, which are otherwise known as RGBs. Nonetheless, the image below shows the white colour highlighted which is the best colour to use when altering your white and black outputs.

As you can see, when you alter the white RGB curve, the peaks of the white and black begin to change. This can easily be viewed when using the Luma waveform graph, shown to the left hand side of the image below. When looking at the image there are two key bars on the right side of the graph -the highest bar being the maximum peak for white, and the bottom being the maximum peak for black. This is very helpful as it'll tell you whether your image is peaking to how white or black the lightest/darkest part of the image is, allowing you to get the maximum contrast you can get by altering the graph.

Graph to the left enables you to alter your highest and lowest black/white peaks
by altering the curve in the graph on the right hand side.

Below is an example of an image which has been altered using only the white RGB curve. As you can see, the image already looks much better just by altering the black and white scopes.

The image after altering the black and white scopes

RGB Parade

Next up in the video is an introduction to the RGB Parade scope. This scope works effectively once the black and white levels have been determined as it enables you to focus on your other prime colours that ultimately alter the colour of the image - red, blue and green. Likewise to the previous Lumetri scope, this effect works in a similar way: each colour should aim to hit the highest and lowest points of the graph to enable the image to have a balance in-between all colours.

Of course, this isn't entirely relevant for problems which we face such as our white balance seeming yellow, however by reaching these peaks it'll then enable you to work out what to adjust to make the white balance look visually what you would expect.

What the RGB Parade looks like.

Here you can see the high and low peaks for all three RGB curves.As you can see, the original
image's red RGB curve isn't quite meeting it's high and low peaks, causing the image to
seem more yellow rather than white.

Additionally, this scope gives you the option of altering basic corrections, such as white balance, temperature, exposure, etc. This can be used to adjust the image once the RGB curves are matching it's high and low points, or even to give the image a stylistic effect which you may expect to find in cinematic films.

Basic correction tool

Below is an example on how using this scope can enable you to edit an image which has a weak white balance. As you can see, the original image had too much yellow due to the white balance being slightly off. However, this scope enables you to alter these levels by looking at the peaks of the RGB colours so that the image is much more neutral in terms of colour, and looks the way you would expect it to look.

Original Image

Edited Image

Vectorscope YUV & RGB Curves

After watching this video, I began to experiment which ways of colour correcting seemed more convienet for me to use. In my opinion, altering the whites and blacks using the Luma waveform and then changing the other colours using the RGB parade scope seemed the easiest method. However, the video also explains how you can use the Vectorscope YUV to change the other RGB colours, rather than just the white. 

This is done by altering the hue saturation curve, shown in the bottom right of the image below. It is quite simply a wheel with the colours in which you drag the white inner line in or out to change the strength of the colour to whichever angle you are dragging the line to.

Vectorscope YUV shown on the left side and RGB curves and
hue saturation curve shown on the right.

This works quite efficiently as it enables you to see how the white and blacks alter by looking back to the Vectorscope, which you can see changes slightly in the image below. Nonetheless, the graph above (on the same image) to me seems the most effective for colour correcting DownStage - it seems the most efficient for making an image look better whilst staying neutral looking so it conforms to the documentary genre.

The hue saturation curve being altered which shows up on the Vectorscope YUV scope.

This graph is called the RGB curve - the same graph used to change the white balance.  As you can see below you simply alter each of the colours to help you gain a neutral colour, or once again to help you create a specific colour tone or cinematic feel.

Altering the RGB curves

Below is a comparison of an image before and after it has been edited. As you can see, by using a mixture of these different scopes, you can almost completely fix the look of an image. The original here is too overexposed and the white balances is quite off. However, by using mainly the RGB curves and the luma waveform, you can solve the problem of an image and even contrast the colours to make the image seem a bit harsher - what I am aiming to do for our interviews, as explained in my 'Interview Colour Grade' post. 

Left being the original image, and the right being the edited image.

Therefore, I will mainly be using the luma waveform, RGB curves and basic correction effects to colour grade DownStage for now, until I come across any other research that may also be helpful.