Grading With DaVinci Resolve 11.3, Part 4 of a Series

Blackmagic’s Davinci Resolve 11 is a versatile and multi-featured program. Video editor and instructor Steve Mullen reviews how to get the most from Resolve 11.3.

Parts 1 here, Part 2 here, and Part 3 here of this series covered round-tripping, using Resolve as an NLE, Resolve preferences, importing compressed and uncompressed media, plus grading both RAW and compressed formats.

Shooting RAW provides maximum flexibility during grading. It also requires hard work. After grading RAW with a single node, add an additional node that you will use to fully restore a clip as described by RGB Primaries Grading below. After this second node, you can add one, or more, additional nodes to use for creative grading.

Grading Compressed Video

During import, the entire data range from “0” to “255/1023/4095” is converted to YRGB 32-bit floating-point values. After conversion, 16/64/256 is displayed as “0” while 235/940/3760 is displayed as “1023.” Super Black (0 to 15/63/255) and Super White (236/941/3761 to 254/1022/4094) values are not displayed.

That’s why after import, when I see data crammed against 0 or 1023, I always dial Shadows/Lift up and/or Highlights/Gain down so I can see what data might be obscured. One of most important upgrades I hope will come with Version 12 are scopes that read-out from -20% to +120%.

During grading when values are pushed below 0 and/or above 1023, because these data are floating-point values, they are preserved despite Resolve no longer displaying them.

When exporting to ProRes (YCrCb) Super Black and Super White values are simply clipped away.

While one can create a “soft clip” function, I find it easier during grading to not allow values to move below 0 (0-percent) or rise above 1023 (100-percent). This solves the issue of unseen values and it also eliminates clipped data during export.

RGB Primaries Grading

I prefer to work with RGB sliders acting independently, so I set “Luminance mixer defaults to zero” as shown in Figure 1.

Illustration 1: Check “Luminance mixer defaults to zero”.

Illustration 1: Check “Luminance mixer defaults to zero”.

Click the RGB Primaries icon to bring-up the Lift, Gamma, Gain, and Offset control sets. Each set has Luma (Y), Red, Green, and Blue vertical sliders. Below these sliders there is a horizontal dial that adjusts YRGB simultaneously.

Figure 2 shows a not yet optimally adjusted image. The white flower is too blue and the image is too dim.

Illustration 2: Not Yet Optimally Adjusted Image.

Illustration 2: Not Yet Optimally Adjusted Image.

To increase image brightness, either drag the Luminance Gamma curve upward (always my preference because I can create a shaped curve) or dial gamma rightward. In Figure 3 you can see brightest segment of the white flower. Because the flower is white, adjust the RGB Gain sliders so all RGB channels are at 1023.

Illustration 3: Increase Image Brightness.

Illustration 3: Increase Image Brightness.

Now use the RGB Lift sliders to make the minimum points of the RGB channels reach zero. See Figure 4. Note: too much contrast can make an image look harsh so lowering the RGB channels to only 128 may be optimal.

Illustration 4: Adjust RGB LIFT Sliders.

Illustration 4: Adjust RGB LIFT Sliders.

The red flower is slightly lacking in saturation. Look at the vectorscope to check vector length and direction. Slide the Saturation slider rightward to increase image saturation. The length of the vector will increase. To alter the flower’s hue, you can slide the Hue slider left or right. See Figure 5.

When grading skin tone, its vector should be aligned along the vectorscope's “flesh-tone line.” This line represents under-the-skin hemoglobin color and is valid for most complexions.

Illustration 5: Increase Saturation.

Illustration 5: Increase Saturation.

Creative Grading

To make creative adjustments to a clip, I switch from RGB Primaries to the more traditional Color Wheels. Figure 6 shows a girl on a beach in what looks like late afternoon sun.

Illustration 6: Traditional Color Wheels.

Illustration 6: Traditional Color Wheels.

Figure 7 shows the image tone shifted towards faux moonlight.

Illustration 7:  Faux Moonlight

Illustration 7: Faux Moonlight

Power Windows

Resolve has a large set of tools beyond those used for grading. One of the most powerful and useful tools is Power Windows. A power window divides an image into two areas, each of which can be independently graded.

Circular, Linear (four-point), polygonal, PowerCurve (Bezier), and gradient power windows can be created. Figure 8 shows a polygon I drew around a bottle. With the division created, the saturation of the bottle can be increased by adjusting the second node. Background saturation can be reduced using the third node.

Illustration 8: Polygon Power Window Tool.

Illustration 8: Polygon Power Window Tool.

When grading old film I encountered a situation where a simple correction wouldn’t work. Figure 9 shows the ungraded image in the upper-left corner. The red car has a slight magenta tint. Correcting this by increasing green will make the women’s face even more green.

The solution: create two independent grading areas. I drew a circular power window over the women’s face as shown in the upper-right corner. The mask, shown in the lower-left corner, confirms positioning. Now I was able to grade the car and face independently. The result is presented in the lower-right corner.

Illustration 9: Circular Power Window Tool.

Illustration 9: Circular Power Window Tool.

When an object moves over a background, or a camera frame moves relative to an object, or both move – it’s possible to create a power window and use Resolve’s tracking tool to generate a set of keyframes that keep the power window correctly positioned despite movement. Keyframes and power windows can be used together to solve complex grading problems. Figure 10 shows the tracker tool after a set of keyframes has been generated.

Illustration 10: Tracking Tool.

Illustration 10: Tracking Tool.

The upper-left image in Figure 11 shows film that has gone green. If I were to reduce green to make the road have a more realistic sand look, the green car would develop a magenta tint. So, I drew a circular power window around the car. (Upper-right image) Next, I used Resolve’s tracking tool to generate a keyframe set that tracks the car as it comes toward the camera, passes very close to the camera, and then drives into the distance.

Now it was possible to grade the background separately as shown by the image in the lower-left corner. (To do a better job, I should have created a second power window to cover the car’s convertible top.) The lower-right image shows the car driving further down the road.

Illustration 11: Circular Power Window Tool and Tracking Tool.

Illustration 11: Circular Power Window Tool and Tracking Tool.

When you purchase the full version of Resolve, additional powerful tools become available. When working with telecined film, the Scratch and Dirt removal tool is a life saver. Figures 12 and 13 show a film frame before and after dirt has been removed.

Illustration 12: Before Dirt Removal.

Illustration 12: Before Dirt Removal.

Illustration 13: After Dirt Removal.

Illustration 13: After Dirt Removal.

From what I saw of DaVinci Resolve 12 at NAB, you can expect there will be some differences in operation. Nevertheless, the concepts introduced in this series are very likely to remain valid.

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