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Original question:

EKB-3P-DLP4500EVM: Video image corrupted in pattern mode

EKB-3P-DLP4500EVM: Stretching of display with DLP in pattern mode and resolution set to 912x1140

Cyrus McHugh
Prodigy 10 points
Part Number: EKB-3P-DLP4500EVM
Other Parts Discussed in Thread: DLP4500

I'm working on the same system that is in the other post.

It was suggested that in pattern mode if we switched our resolution to 912x1140 it would no longer be stretched. I have found that it is still stretched regardless of the correct resolution. We have a nvidia t400 graphics card and have made sure that through the nvidia control panel it is not trying to rescale it. There is a discrepancy between the nvidia control panel and the windows display settings as the control panel thinks the display is in landscape mode and windows settings thinks it's in portrait mode. If I switch either one the other will switch as well IE Nvidia portrait will make windows landscape(flipped). 

If I make a circle that is 912 pixels it will fill the width of the display and 1140 will fill the height.

Measuring the whole display it seems to have an aspect ratio of 1.6.

We have two displays, one 1920x1080 and the the DLP set to 912x1140 running in extended mode.

 

Thanks for your help.

Cyrus

  • 0
    TI__Expert 8480 points

    Hello Cyrus,

    Welcome to the E2E forums and we hope to assist you with your questions.

    I am trying to understand the issue can you please answer the following to help clarify:

    1. Could you describe what are the dimensions of that image with the white rectangle and circle?

    2. What are you expecting or wanting to see?

    3. What is the original image and resolution you are sending in? I assume this is from hdmi from your computer?

    4. I may not fully understand the issue still but if you take the Nvidia graphics card out of the equation and just send an image through your computer, does that work without all the switching of orientation?

    Additionally, you can save the GUI settings into an ini file and send that to me so I can better understand your GUI setup parameters.

    Regards,

    Alex Chan

  • 0 in reply to Alexander Chan
    Prodigy 10 points

    Hi Alex,

    1. That was an image of the computers background which should have been a circle with a square. I will attach an image of a circle on a gray background that should have a diameter of 912 pixels. We are using a software called PsychoPy to draw the images. When I ask it for the resolution it responds with 912x1140. 

    2. We were hoping to see an image of a circle but it seems to be stretched horizontally and squished vertically. 

    3. This was just the desktop background of a circle but this stretching occurs when we try to draw an image with a program as well. Yes this is sent from the mini-hdmi from the DLP to our computer's graphic card through a mini-display port.

    4. Currently I don't have a way to put it through the onboard graphics card but I will order the adapter/cord to put it through the VGA port or try through a computer with a different graphics card.

    It is the same .ini file from the other form.

    https://drive.google.com/file/d/1dr-KNGXl9Yabp9XWWlVEIBcJGYBsP9fU/view

    I'm also attaching images of our display settings. I've included two images of the timing settings when trying create a custom resolution. The first being the one it was already set to when opening the custom resolution (CTV reduced blank) and then the settings when timing is set to automatic. I'm not sure which one is being used when I select 912x1140.

    Thanks for your help!

    Cyrus

  • 0 in reply to Cyrus McHugh
    TI__Expert 8480 points

    Hello Cyrus,

    So to see the correct circle, please set your system to video mode and then ensure your display settings are 1280x800.

    You can then double check this by checking the video signal information by pressing "Get Video Info" and then ensuring you see 1280x800 in the horizontal and vertical resolution fields. 

    Here I am displaying a white circle on black background:

    Note that this will only work for video mode, for pattern mode the resolution can only be set to 912x1140.

    Video Mode - Input Image 1280x800-> Diamond Conversion logic ON (map input image to) -> Native DMD resolution 912x1140

    Pattern Mode -> Input Image (this must be 912x1140) -> Diamond Conversion logic OFF -> Native DMD resolution 912x1140

    If you want to use pattern mode you will need to create images that in 912x1140 that compensate for the diamond conversion logic off to display correctly.

    This may also help explain more:

    https://e2e.ti.com/support/dlp-products-group/dlp/f/dlp-products-forum/532182/dmd-input-image-pixel-and-micro-mirror-array-pixel-relation

    Thanks,

    Alex Chan

  • 0 in reply to Alexander Chan
    Prodigy 10 points

    Hi Alex,

    In video mode everything works fine but we have to be in pattern mode.

    Where would I find the diamond conversion logic setting or is that inherently off when in pattern mode?

    In the other thread you linked there is a line, "Thus, if you take an image designed for orthogonal array configuration, it will look stretched on a diamond pixel array configuration." So is it not surprising that even with the display set to the native DMD resolution we are getting stretching.

    Looking back on the images I sent you and thinking about the DMDs orientation. If there are only 912 pixels horizontally and 1140 vertically then why does the whole display look wider than it is tall IE why does the aspect ratio look about ~1.6 vs what it should be at the native resolution of 0.8?

    Thanks,

    Cyrus

  • 0 in reply to Cyrus McHugh
    TI__Genius 12785 points

    Hi Cyrus,

    Please allow us until the end of the week to investigate and respond.

    Regards,

    Austin

  • 0 in reply to Austin Snyder
    Prodigy 10 points

    Hi Austin,

    I've been looking through the forums and tt seems like this an issue of how rows and columns are defined. In the image below it looks like the columns are two mirrors wide. So the vertical size instead of being 1140 pixels tall its only 570 pixels tall. This would make sense aspect ratio of the output image despite the resolution being 912x1140.

    I'm trying to see if there is a work around with custom resolutions and the nvidia GPU display scaling but we might just have to change the way we generate images.

    /cfs-file/__key/communityserver-discussions-components-files/94/3652.Capture124.JPG

    Thanks,

    Cyrus

  • 0 in reply to Cyrus McHugh
    TI__Expert 8480 points

    Hello Cyrus,

    Yes you are correct, you can see the following image from the dlp4500 dmd datasheet on page 22 for more information.

    https://www.ti.com/lit/gpn/dlp4500

    Yes you will have to take care of how you generate images and keep this dimension structuring in mind.

    I will close out this ticket.

    Regards,

    Alex Chan