Dell S718QL 4K UHD Laser Projector Review – Calibration Settings

March 6, 2018

/ By Art Feierman

Dell S718QL 4K UHD Home Theater Projector Review – Calibration Settings: Calibration Presets Notes, Best Mode Calibration, Brightest Mode Calibration & 4K Calibration

Dell S718QL Calibration Notes

My calibration report for Dell’s S718QL is going to be a bit shorter than usual. Simply put there are very few picture controls to begin with and they are global further diminishing their usefulness. During my time with the projector I spoke with a Dell engineer who answered all my questions listened to my feedback in regards to my experience with the S718QL. He could not promise me anything but seemed to indicate that it might be possible to rectify some of my concerns in future updates, here’s hoping.  [Editor's note: While it's possible Dell would update the firmware of this projector, I would consider it highly unlikely they would add what Eric says is needed. Therefore,when it comes to the picture, what I describe elsewhere in this review, is what you should expect in terms of performance. Adding a CMS or separating the settings by mode would be massive rework of the firmware by Dell.  At best, perhaps the next generation... -art]

The Dell S718QL has 4 video presets (Bright, Presentation, Movie, sRGB & Custom). There are 3 lamp modes and one of them is hidden. Let me explain. In the menus you will find 2 lamp modes (normal & ECO). However, if you choose Bright as your picture mode it runs the lamp even brighter regardless if you have the lamp set to normal or ECO. The fan speed (and noise) will increase to deal the increased heat output.

[sam_pro id=1_119 codes="true"]

Best (dark room) Mode Calibration for 1080p and REC.709 – Night Mode

sRGB Mode Pre-Calibration RGB Balance / Grayscale Tracking (target D65)
sRGB Mode Pre-Calibration RGB Balance / Grayscale Tracking (target D65)

For my best/dark room 1080p calibration, I used sRGB mode (normal lamp). I used sRGB mode rather than Movie because it’s color gamut was slightly better. Like so many other projectors I have calibrated the S718QL clips the whites ever so slightly (230 or so) and lowering contrast does nothing to help this matter. There is only one set of white balance (gain) adjustments and no gamma controls. So, although I would have preferred a gamma of 2.4, I set my target to 2.2 based on the projectors performance and was able to get an average of 2.14. The S718QL before white balance/gamma DeltaE ranged from 3.5 on the low end to 11 on the high end. After calibration I was able to get it to 2 or less across the board (10-100IRE). DeltaE of 3 or below is considered excellent. White balance averaged around 6400K.

I wanted to set contrast 2 clicks lower from its default of 50 because it helped my gamma and white balance a small amount at the 90 and 100IRE range. I did not however because by making any changes to contrast, brightness, color or tint would toss me out of sRGB mode and into custom mode. Now other projectors have done this before by coping your settings from your chosen mode, in this case sRGB and applying them to custom mode. Problem here is that is does not do this, it just places you in custom with its far from desirable picture performance. So, in order to stay in sRGB mode I can’t touch any picture controls except for white balance.

The S718QL has no CMS controls. You have to live with what it gives you, which is why I choose sRGB because it displays the best color gamut of all the picture modes. Now if you look at my color gamut charts (below) you will see there are slight differences between before and after. You may ask with no CMS controls why aren’t they the same? Well the white balance gain calibration I did has an effect on color gamut. Over all the gamut is not terrible but it’s far from great too. Blue and yellow fair the best. Magenta is over saturated at 100%. Red is under saturated across it’s range. Green is under saturated across its range except for 100% which is over saturated. Oddly the hue of cyan got worse after calibration with it now running towards green.

[sam_pro id=1_74 codes="true"]

sRGB Mode Post-Calibration Gamma Log 2.16 Average Gamma (target 2.20)
sRGB Mode Post-Calibration Gamma Log 2.16 Average Gamma (target 2.20)
IREPre-CalibrationPost-Calibration
10 IRE7317K6702K
20 IRE7081K6826K
30 IRE6639K6537K
40 IRE6764K6472K
50 IRE6909K6457K
60 IRE6910K6469K
70 IRE6915K6468K
80 IRE7000K6512K
90 IRE6989K6532K
100 IRE6921K6517K

Measurements taken at Mid Placement with Normal Lamp.

Average Gamma Pre-Calibration: 2.14

Average Gamma Post-Calibration: 216 @ 2855 Lumens

[sam_pro id=1_35 codes="true"]

[sam_pro id=1_122 codes="true"]

TypePre-CalibrationPost-Calibration
Contrast5050
Brightness5050
Color5050
Tint5050
Color TempMidMid
TypePre-CalibrationPost-Calibration
Sharpness55
White Intensityn/an/a
Color SpaceAutoAuto
Wall ColorWhiteWhite
RGBGainOffset
Red48n/a
Green52n/a
Blue46n/a

White Balance calibration settings for Night mode.

sRGB Mode Post-Calibration DeltaE 2000 (target below error of 3)
sRGB Mode Post-Calibration DeltaE 2000 (target below error of 3)

Delta E is a metric for understanding how the human eye perceives color difference. The term delta comes from mathematics, meaning change in a variable or function. The suffix E references the German word Empfindung, which broadly means sensation. Simply put, look at Delta E as a measure of grayscale/color accuracy. 3 and under is considered ‘Excellent’ and imperceptible by the human eye.

[sam_pro id=1_119 codes="true"]

Brightest Mode Calibration for 1080P and REC.709 – Bright Mode

For my bright room 1080p calibration, I choose bright mode with it’s hidden ‘brightest’ lamp output. Because the white balance calibration I performed on sRGB mode is global I can’t do it here, otherwise it ruins my dark room/best calibration. White balance in bright mode was a bit off putting with its excessive green tint, but I found a way to improve it a little bit. There is a “feature” found in many business/education projectors called wall color that is now making its way over to some ‘crossover’ projectors like the S718QL.  I usually ignore these kinds of setting because all they do is further deviate from the SMPTE standards I try so hard to adhere to. Anyway, in this case setting wall color to dark green helped reduce the green push a little bit. You will need to set wall color back to white when using my best/dark room calibration because this setting is global.

Bright Mode Post-Calibration RGB Balance / Grayscale Tracking (target D65)
Bright Mode Post-Calibration RGB Balance / Grayscale Tracking (target D65)

Before & after DeltaE is off the chart at 12+ across most of the spectrum. Gamma averages 2.14 but is far from linear with it getting too dark at 50-60IRE and a big spike of over brightness at 90IRE. Color gamut has many, many problems, just take a look at my charts (below).

Bright Mode Post-Calibration Gamma Log 2.16 Average Gamma (target 2.20)
Bright Mode Post-Calibration Gamma Log 2.16 Average Gamma (target 2.20)
IREPre-CalibrationPost-Calibration
10 IRE7189K6694K
20 IRE7156K6724K
30 IRE7111K6555K
40 IRE7193K6559K
50 IRE7050K6601K
60 IRE6854K6265K
70 IRE6856K6185K
80 IRE6872K6297K
90 IRE7191K6255K
100 IRE7220K6687K

Measurements taken at Mid Placement with Normal Lamp.

Average Gamma Pre-Calibration: 2.43

Average Gamma Post-Calibration: 2.30 (target 2.20) @ 4949 Lumens

[sam_pro id=1_74 codes="true"]

TypePre-CalibrationPost-Calibration
Contrast5050
Brightness5050
Color5050
Tint5050
Color TempMidMid
TypePre-CalibrationPost-Calibration
Sharpness55
White Intensityn/an/a
Color SpaceAutoAuto
Wall ColorWhiteDark Green
RGBGainOffset
Red48n/a
Green52n/a
Blue46n/a

White Balance calibration settings for Day mode.

Bright Mode Post-Calibration DeltaE 2000 (target below error of 3)
Bright Mode Post-Calibration DeltaE 2000 (target below error of 3)

4K with HDR – HDR Mode

Lastly, I attempted a 4k/HDR calibration. For starters, no matter what mode you are in when you send the S718QL an HDR signal it automatically switches into a HDR mode. Well it’s not a labeled mode like sRGB or Cinema. What it does is gray-out (disable) all picture setting except for white balance and HDR mode. There are 2 HDR modes, auto and bright. Auto measured very flat (see EOTF/gamma chart). Bright measured a bit brighter from 0 to 55 IRE.

Like with my bright room calibration I did not want to touch the white balance controls and ruin my best/dark room 1080p calibration. This left me my one little cheat. The white balance in HDR mode is extremely blue so I set wall color to light blue. This reduced blue a tiny bit but like my bright room calibration DeltaE was very high, +12 from 50 to 100IRE. Dell does not advertise the S718QL as covering the P3 color gamut for 4K/HDR but when speaking with Dell’s technician he said it should cover 130% of REC.709.

[sam_pro id=1_122 codes="true"]

HDR Pre-Calibration RGB Balance / Grayscale Tracking (target D65)
HDR Pre-Calibration RGB Balance / Grayscale Tracking (target D65)

So, I used the P3 color gamut chart to measure the projectors capabilities. Well the results are not very good, it’s not the fact the colors don’t make it out to the P3 targets that bothers me, it’s the hue of some of the colors are off by quite a bit. It appears the color gamut is heavily tied to the white balance, which in this case is very blue. Look closely at the white dot in the CIE charts. This dot represents the white balance which is in the blue area far from its D65 target. Now all of the 6 colors seem to emanate from that point, driving some of them far off course. Although magenta seems to have the largest error, yellow is the most troubling with it being pulled so close to green.

HDR Mode (HDR/Auto) Post-Calibration (Electro optical Transfer Function) aka gamma
HDR Mode (HDR/Auto) Post-Calibration (Electro optical Transfer Function) aka gamma
IREPre-CalibrationPost-Calibration
10 IRE9758K8730K
20 IRE15418K12880K
30 IRE15748K14995K
40 IRE15293K11252K
50 IRE16267K13166K
60 IRE15883K14180K
70 IRE17090K13618K
80 IRE16017K13846K
90 IRE16860K14651K
100 IRE17168K14881K

Measurements taken at Mid Placement Normal Lamp.

ETOF (gamma) Post-Calibration: Auto tracked fairly flat except for the low end which was slightly brighter than the target @ 5168 Lumens.

[sam_pro id=1_119 codes="true"]

TypePre-CalibrationPost-Calibration
Contrast5050
Brightness5050
Color5050
Tint5050
Color TempMidMid
TypePre-CalibrationPost-Calibration
Sharpness55
White Intensityn/an/a
Color SpaceAutoAuto
Wall ColorWhiteLight Blue
RGBGainOffset
Red48n/a
Green52n/a
Blue46n/a

White Balance calibration settings for HDR mode.

HDR Mode Post-Calibration DeltaE 2000 (target below error of 3)
HDR Mode Post-Calibration DeltaE 2000 (target below error of 3)

[sam_pro id=1_74 codes="true"]

CIE Charts for Best, Brightest, and HDR Modes

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