Recherche avancée

Sur d’autres sites (7199)

• Generate color palette from an image for FFmpeg

  18 mars 2018, par Peter

  I want to generate color palette from an image but FFmpeg allows to generate palettes only from videos. The only Bash tool I know that can generate color palettes from images is ImageMagick, but it generates palettes in a *.txt and I need a *.png palette.

  Is there a bash tool to generate palettes with fine control ? Or maybe there is a way to do it in FFmpeg ?

  P.S. I need that palette to create GIF in FFmpeg.

• Create 256 color palette video

  2 mars 2020, par rlcabral

  I already have this working by converting the source video to GIF with :

  ffmpeg -y -t 5 source.mp4 -vf fps=10,scale=480:-1,smartblur=ls=-0.5,crop=iw:ih-2:0:0 -hide_banner -loglevel panic output.gif

  And then converting the GIF to MP4, like so :

  ffmpeg -y animated.gif -hide_banner -pix_fmt yuvj420p -loglevel panic -an -loglevel panic final.mp4

  What I want is to convert source.mp4 directly to final.mp4, and have the same 256 color palette as a normal GIF.

  I tried merging both commands together, and although it generates a MP4, the result is a 16 bit video, surprisingly smaller than a 8 bit video.

  Do I need to generate a palette first with palettegen and then re-encode the video with this palette ?

• YUV420p to other formats, color shift problems

  1er juin 2013, par Sam

  So I'm writing a color detection application using an AR Drone. The drone sends my python/opencv socket server an image from its camera in YUV420p format.

  What I do to access the image as an opencv IPLImage is the following (and yes this is inefficient but I didn't / don't want to have to write new conversion tools myself) :

  1. Save the yuv image to a file (some_image.yuv)
  2. subprocess.call(insert ffmpeg call here)
  3. Read the resultant file (bmp, png, it doesn't matter) back in using cv.LoadImage

  My problem right now is a very noticable color shift. I'm waving a red felt sheet in these pictures. The first one shows a heavy yellow tint. The second isn't as bad but is very rare — mostly when I have the red sheet it's heavily tinted.

  • Tinted image : http://i.stack.imgur.com/BQikM.png
  • Less-tinted image : http://i.stack.imgur.com/ezHyy.png

  I'm wondering both of these things :

  1. if there's either a better way to do this
  2. If the color tinting issue can be resolved

  My ffmpeg conversion line looks something like

  ffmpeg -s 640x480 -vcodec rawvideo -f rawvideo -pix_fmt yuv420p -i image.yuv -vcodec bmp -f image2 output.bmp

  I've also tried :

  ffmpeg -f rawvideo -s 640x480 -pix_fmt yuv420p -vf colormatrix=bt709:bt601 -i image.yuv -f image -vcodec png output.png

  The color shift is always there, unfortunately !

  The color shift is my big problem right now as I later convert the image to HSV and use thresholding to choose a color range that works for me.