DLP4500 IMAGE DISTORTED

user4079080

Other Parts Discussed in Thread: DLP4500

Hi,

I am currently conducting an experiment with DMD dlp4500. I found that the images projected are distorted compared to the images I input. I later found that the problem occurred when I add the image onto the firmware. How do I fix this?

this is the image I want to input with the resolution the dmd required

this is the screenshot after loading the image onto the GUI

this is the image projected

As you can see, the image I generate is are square boxes however the images projected are rectangles, the image is apparently distorted. Can you tell me how to fix this problem?

Sincerely,

Allen

over 9 years ago

0 Fizix over 9 years ago

TI__Guru 54685 points

Hello Allen,

The image is distorted vertically by 1/sqrt(2) and horizontally by sqrt(2). This effectively makes a square (1:1) come out (1:2) - i.e. is stretched in the horizontal direction by a factor of two relative to the vertical.

What you need to do is generate an image that is "pre-distorted" by a factor of 2 vertical direction. In other words make the "squares" in the image you feed to the DLP4500 twice as high as they are wide. When you feed this in, the result will be an image whose squares are (1:1) - i.e. really are squares.

I hope this helps.

Fizix

0 Fizix over 9 years ago in reply to Fizix

TI__Guru 54685 points

Allen,

For some reason I got your reply by email notification but it doesn't show up here.

Your response question was:

So the image is distorted in the dmd? or is it due to the optical path?

Refer to Figure 3 on page four of the DLP4500 data sheet:

The apparent distortion is a consequence of the way the columns and rows are mapped on a "diamond" device. Although there are other ways that it could have been mapped, this way was chosen to make the DMD circuitry similar to DMD on an "orthogonal" device.

The following two threads have a discussion of this:

https://e2e.ti.com/support/dlp__mems_micro-electro-mechanical_systems/f/924/p/321482/1119954#1119954

https://e2e.ti.com/support/dlp__mems_micro-electro-mechanical_systems/f/924/p/440253/1588635#1588635

I hope this helps.

Fizix

0 user4079080 over 9 years ago in reply to Fizix

Prodigy 210 points

Hi Fizix,

Great Thanks for the reply, it really helps!
I had two more questions, wondering if you can help me out
1. I am trying to load a 1-bit black and white image on to the dlp lightcrafter 4500, how can I do this?
2. Although the image is static in video mode, the dmd seems to refresh at a high frequency. How can I make the dmds stop refreshing (required in the experiment) and project a static image?

Sincerely,
Allen

0 Clinton Rodgers over 9 years ago in reply to user4079080

TI__Genius 13235 points

Hi Allen,

For reference, I'm going to link your other post where we are discussing the answers to your questions 1 and 2.

e2e.ti.com/.../1650045

Thanks,
Clinton

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DLP4500 IMAGE DISTORTED