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LG 24GM77 24-Inch 144Hz Gaming Monitor Review

Results: Grayscale Tracking And Gamma Response

Our grayscale and gamma tests are described in detail here.

We’d like to think our monitor reviews inspire manufacturers to improve their out-of-box accuracy. Indeed, it seems like more of the screens landing in our lab look fantastic at their default settings. The above chart shows a tiny bit of red, but check out the actual error levels – they’re well under the threshold of visibility at 3dE. There is no need to calibrate the 24GM77 or even to change its picture mode from Custom.

We adjusted our sample anyway, making improvements to all grayscale levels except 90 and 100 percent, which rose ever so slightly. Since there’s no reduction in contrast, you might as well calibrate if you have the means.

Once you engage the game modes, accuracy shifts from excellent to merely good. The FPS1 mode shown above is just one example. Aside from a blue tint at 100 percent, grayscale tracking remains solid. Unfortunately, as you’ll see on the next page, color saturation does not fare as well.

Here is our comparison group:

A 1.12dE unadjusted grayscale average is hard to beat. We’ve only measured two professional screens that could do better.

After making slight adjustments to the RGB controls, we realized a .37dE reduction in grayscale error. Since overall contrast only dropped by .07 percent, we’ll call that a win. Yes, this really is a $300 gaming monitor. Bravo LG!

Gamma Response

Gamma tracking is the only place where the 24GM77 has room for improvement. It’s perfect until the 70-percent level, where it takes an abrupt slide downwards (too bright). It’s not bad enough to crush detail, though bright objects like clouds become a bit flat-looking. It’s a minor criticism and could be fixed with a firmware update.

This is the same FPS1 game mode we measured above. The gamma rides high (too dark) from 50 percent on up, making middle and bright tones look murky. The game modes also engage some rather unattractive edge enhancement, so we prefer to avoid them in our usability tests.

Here is our comparison group again:

The 90-percent gamma value of 1.50 spoils what could be a much better result. In this one metric, the competition is well ahead. Hopefully LG addresses the problem through an update of some sort.

We calculate gamma deviation by simply expressing the difference from 2.2 as a percentage.

Since most of the gamma trace is right on the 2.2 mark, the average value is 2.11, representing a 4.09-percent deviation. In general, image quality isn’t impacted too much, though it could be better in bright content. On the bright side, color and grayscale accuracy are not affected by this.

Christian Eberle
Christian Eberle is a Contributing Editor for Tom's Hardware US. He's a veteran reviewer of A/V equipment, specializing in monitors.