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Category: Computer Vision

Color Isolation with FFMpeg

Color Isolation with FFMpeg

I had written a post awhile back about color isolation using imagemagick. Here is a recap, but this time using FFMpeg. This turned out to be a good color pattern to do testing against. the reason I prefer this is because it contains white and black space to visually understand the results of the filter. Lets try this command. ffplay -i “color-pattern.jpg” -vf “colorhold=0xFF0000:similarity=0.25” Now our image shows only the defined color threshold, in this example it’s red. Here are…

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Software Gimbal

Software Gimbal

In this post I’ll demonstrate how to stabilize and enhance low resolution video using FFMpeg. I will also discuss the pros and cons of hardware options available. From there the discussion will show examples of software options that have supplanted hardware. Lastly, I will introduce some examples of AI that others have used. The Z51 660mm Below is a side by side comparison of video taken from one of my fixed wing remote control (RC) planes. Here is the script…

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Camera Angular Calibration

Camera Angular Calibration

These are a couple of resources that I’ve used for RC camera information that you may find useful, https://www.chucklohr.com/808/c16/ and https://oscarliang.com/how-to-use-808-16-keychain-camera-manual-and-wiki/. Those links are specific to the 808-16 key chain camera which I have used for bike rides as well as drone flights. There is mention about field of view measurements in the first link. It references methods used which I was not able to reliably validate. http://www.rcgroups.com/forums/showpost.php?p=22171449&postcount=6843 and https://www.rcgroups.com/forums/showpost.php?p=22446815&postcount=7732 both use the Pythagorean theorem. The camera and background are…

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Cleaning Up Underwater Video

Cleaning Up Underwater Video

Last summer was a chance for me and my family to do some water activities in the area. Snorkeling was a big favorite for my son. One of the locations had a fresh stock of fish that drew our attention. Unfortunately, the water in the lake grew cloudy due to our movement and it was a challenge to see. On a follow up visit, we brought one of my 808-16 video cameras. It’s a 720p camera and I wasn’t too…

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The Golden Plate

The Golden Plate

I saw these two videos about the Voyager spacecraft and the Golden Plate each of them contain and found they fit with the other material posted here. “That’s here. That’s home. That’s us. On it everyone you love, everyone you know, everyone you ever heard of, every human being who ever was, lived out their lives. The aggregate of our joy and suffering, thousands of confident religions, ideologies, and economic doctrines, every hunter and forager, every hero and coward, every…

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Cutting through the smoke with Retinex

Cutting through the smoke with Retinex

This year, most of August was unfit for bike riding due to wildfire smoke in the air. There was a 10 day stretch where the visibility scale reached zero. Standing on the shores at Shilshole, the smoke was so thick that land wasn’t visible across the Puget Sound. I wondered if land was still visible from a digital camera, even though I couldn’t see it. There is an imaging processing technique call Retinex that is used to enhance the dynamic…

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FFMpeg motion detection

FFMpeg motion detection

FFMpeg motion detection offers a way to create videos that are smaller and shorter becuase it only captures changed scenes. This post discussed the topic, https://superuser.com/questions/984841/ffmpeg-remove-parts-without-motion. Here is the command I used based off of this conversation. ffmpeg -i “http://viewr1:viewr1@192.168.6.184/mjpeg/stream.cgi?chn=0” -vf “select=gt(scene\,0.004),setpts=N/(25*TB)” IPCam4_Motion.mp4 The one thing I noticed was the timestamp in the video is being detected as a scene change, this introduces a higher noise floor. I found that my lowest scene value to be .004. This site, http://www.bogotobogo.com/FFMpeg/ffmpeg_thumbnails_select_scene_iframe.php…

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DVR Video from Images Captured from IP Cameras

DVR Video from Images Captured from IP Cameras

Working with thousands of image files captured from IP Cameras can be problematic. I’ve experienced issues with Caja hanging when simply browsing the folders that contain the captured images. To work around this, I compile video with FFMpeg from the image stock into a separate folder. First I’ll create a file list using this command ls /home/local/Videos/Security/IPCam3_20180726*.jpg > /home/local/Scripts/IPCam3_20180726.txt The results will then need to be processed so FFMpeg can use the file as a reference. Before – Not ready…

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Security Monitoring with IP Cameras

Security Monitoring with IP Cameras

Security Monitoring with IP Cameras The market offers many choices when it comes to IP cameras. Most people who purchase these devices typically use the bundled software or hardware. This can be convenient but has it limitations. Many of the manufacturers do not support other brands of devices. In this post I’ll be covering how to gather imaging and video directly from IP cameras without the need for the vendors software or hardware solution. The camera I’ll be demonstrating in…

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Spectrograms with FFMpeg

Spectrograms with FFMpeg

In this post I’ll be covering how to create image files that represent the sound levels and frequencies of a media file.  These images are known as spectrograms.  They provide a way to visually locate moments in time.  This can be useful for a number of reasons. FFMpeg has a feature that lets us create spectrograms with the showspectrumpic filter.  Details about this filter can be found here, https://ffmpeg.org/ffmpeg-filters.html#showspectrumpic.  You can also get information about the filter by typing in…

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