[visionlist] Seeking advice on displays with narrowband primaires
abigailfinch at btinternet.com
Thu Aug 16 10:18:03 -05 2018
I posted a question about displays with narrowband primaries a few weeks ago. Thank you for the responses. This email is just to summarise what I've learnt.
In the end I have opted to stick with the display I have. However, I did get some information about some other options which may be useful to others.
RGB LED projectorsRGB LEDprojectors use red, green and blue LEDs as their primaries. These may not alwaysbe narrowband. However, one advantage of using a projector is that a triplepass filter can be placed directly in front of the projector to narrow the primaries.
Texas Instruments LightCrafterTheprojector we are using is the LightCrafter 4710. This has 3 LED primaries. The red and theblue are relatively narrowband (FWHM between 20-25nm) whereas the green is muchbroader (FWHM ~80nm). The green LED also overlaps substantially with the redwhich means that even with the triple pass filter there is light from the greenLED in the red filter channel.
Anotherissue with this projector is that it processes the images before displayingthem rather than simply displaying the desired pixel values. This is not idealfor controlled vision experiments.
The LightCrafter4500 has a lower spatial resolution than the LightCrafter 4710. However, it hasthe advantage of allowing the presentation of exact images without theprocessing, and offers a low level control of the micromirrors. One caveat isthat this control is not available with a standard HDMI input and in this caseit still seems to process the images. The only way to achieve the low levelcontrol (it seems) is to directly manipulate the bit patterns on the controller.
LaserprojectorsLaserprojectors are also an option and although some are very expensive there arealso now some cheaper options. I haven’t looked much into these and I’m not sure how much image processing might go on within the projectors.However, this may be a good option.
OLEDs useLED primaries which can be quite narrowband. However, these often have built inimage processing that may not be possible to disable. It is also difficult tofind out what the spectra of the LEDs are before purchasing so it could berisky.
Some LCDscreens are now being made to have larger colour gamuts. For example, the ASUSProArt PA32UC. However, I have not been able to find information of the spectraor bandwidths for the primaries of any of these displays so again it’s risky.
The VIEWPixxand VIEWPixx/3D displays by VPixx Technologies use RGB LEDs as a backlight.This gives narrower RGB primaries than using a white LED backlight. Thecomponent used is the CREE CLP6C-FKB-CM1Q1H1BB7R3R3. The link to the datasheetwith the LED spectra is here: https://media.digikey.com/pdf/Data%20Sheets/CREE%20Power/CLP6C-FKB.pdf.
Thanks again for the responses.
On Monday, 23 July 2018, 11:19, Abigail Finch <abigailfinch at btinternet.com> wrote:
I'm Abi, a PhD student in the Physics department at Durham University, UK. I mostly run psychophysical experiments investigating the optics of the eye and in particular chromatic aberration.
I'm trying to find a suitable display to present stimuli for an experiment. The most important features are that the display has narrowband primaries (the narrower the better) and a relatively good black level. Does anyone know of a display that might be suitable?
We've been using a DLP projector with LED primaries but are having issues with the black levels and some inbuilt image processing which we can't turn off. We were wondering whether an OLED display might be a better option but haven't found any that actually publish the spectra of their primaries.
Please email me personally at abigail.p.finch at durham.ac.uk to avoid spamming the list and I will write up a summary of the responses I get and post that on the list.
Thanks very much for your help!
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