Get raw 24 Bit image data into a Form

| extent result |
extent := 320 @ 208.
result := StandardFileStream readOnlyFileNamed: 'sample.yuv' do: [ :file |
    file binary.
    extent area * 3 = file size ifTrue: [
        | word bits form |
        form := Form extent: extent depth: 32.
        bits := form bits.
        word := 16rFF bitShift: 24.
        1 to: bits size do: [ :i |
            word
                digitAt: 3 put: file next;
                digitAt: 2 put: file next;
                digitAt: 1 put: file next.
            bits at: i put: word ].
        form ] ].
result display.

Levente

P.S.: This is usually the point when someone comes up with a pure bitblt solution providing further significant speedups.

On Sat, 29 Aug 2015, tim Rowledge wrote:

On 29-08-2015, at 8:13 AM, Herbert König [hidden email] wrote:

Hi,

how do I go about reading a raw RGB 888 (24 bits deep output from raspiyuv) file into a Form?

Well we need to understand the file format first to decode it and so far as some quick googling tells me the yuv files are completely raw; no header to tell us anything, just a long list of bytes. Since you can control the width and height of the image the camera takes (apparently, though it looks like it gets rounded up to 32 pixels in width and 16 in height?) I guess we can at least in principle assume the w & d for the data. The RGB888 is pretty much the Squeak pixels format for 32bpp anyway so there shouldn’t be too much of a problem.

Basically
take your picture and write to file
open file as binary in Squeak `myFileStream := (FileStream readOnlyFileNamed: ‘my.yuv’) binary`
create a Form of appropriate size & depth  `myForm := Form extent: width@height depth: 32`
read bytes from the filestream and stick them in the form’s bits array. There will be issues of byte-endianness to get right (squeak bitmaps are for some demented reason big-endian and I’d guess the pi YUV files are little-endian) and you’ll have to fill in the top (or bottom, see endianness) byte to set the alpha correctly.

It’ll be something along the lines of checking the sizes match up, reading the data into the form’s bits array and making sure the bits all line up.

Here’s a quick example from my pi2, since it tickled my curiousity

in terminal - `raspiyuv -w 320 -h 208 -rgb -o smple.yuv`
in Squeak
Form extent: 320@208 depth: 32 -> inspect it
in the inspector -
|myfile alpha|
myfile := FileStream readOnlyFileNamed: ‘/home/pi/sample.yuv’.
myfile binary.
bits size * 3 = myfile size ifFalse:[^nil].
alpha := 16rFF<<24.
1 to: bits size do: [ :i| |val|
val := myfile next.
val := val <<8 + myfile next.
val := val <<8 + myfile next.
val := alpha bitOr: val.
bits at: i put: val].
myfile close
self display

I get a pretty decent image displayed. Takes 250 mSec to read in on my pi2 with a cog-spur squeak. A bit over half that is the cost of using the largeinteger ‘alpha’ to set the proper alpha value for each pixel. You *can* leave that out if you’re going to simply do ‘myform display’ since the raw bitblt ignores the alpha. If you are going to be examining the pixels as just rgb values, save the time - I see 120mS in that case.


Obviously once you have the general format sorted it ought to get moved into Form and tidied up as From class>>readRGBFromFileNamed: or similar.


tim
--
tim Rowledge; [hidden email]; http://www.rowledge.org/tim
Useful random insult:- If you give him a penny for his thoughts, you get change back.

http://www.raspberrypi.org/forums/viewtopic.php?f=43&t=119050
6by9 suggested to use raspiyuv and I wanted to at least verify that raspiyuv doesn't have this bug. It doesn't.

I can live with the bug because first thing I compute the difference between two consecutive images via BitBlt. This makes the problem vanish.

On that I do a very specialized motion detection to identify cats using the garden as a toilet :-)). I only noticed the problem because I save the photos creating an alarm. 

Cheers,

Herbert

Hi Herbert,

Wouldn't it be better to use raspistill instead of raspiyuv, and generate a jpg or png file directly?

Levente

On Sun, 30 Aug 2015, Herbert König wrote:

Hi,

this works with image size of 320 @ 208. On my A+ with a size of 1280*832 Tim's version takes 10-12 seconds without displaying the Form. Levente's
version takes about 1.5 to 3 seconds. This is already too slow for me.
 
Here:
https://www.raspberrypi.org/documentation/raspbian/applications/camera.md (search for --rgb)
suggests that padding for multiples of 16 may occur.
I thought I would get away with just ignoring the end of the file by changing the test to (extent area * 3 <= file size) as long as x is dividable
by 16. But already with 1296@832 which can both be divided by 16 some padding after each line sets in and the resulting image is garbled if that's
not taken into account.

I want 1296@972 image size to take advantage of the camera module's binning capability (adding four physical pixels to reduce noise) in my long
night exposures.
Finding out the buffer length after which they start padding and accounting for that will not help as it will make the code slower, even if not
much. If you happen to know the buffer size of raspiyuv, please tell me so I can play a bit.

Thanks to both for chiming in. I learned something :-))

Herbert


      | extent result |
      extent := 320 @ 208.
      result := StandardFileStream readOnlyFileNamed: 'sample.yuv' do: [ :file |
          file binary.
          extent area * 3 = file size ifTrue: [
              | word bits form |
              form := Form extent: extent depth: 32.
              bits := form bits.
              word := 16rFF bitShift: 24.
              1 to: bits size do: [ :i |
                  word
                      digitAt: 3 put: file next;
                      digitAt: 2 put: file next;
                      digitAt: 1 put: file next.
                  bits at: i put: word ].
              form ] ].
      result display.

      Levente

      P.S.: This is usually the point when someone comes up with a pure bitblt solution providing further significant speedups.

      On Sat, 29 Aug 2015, tim Rowledge wrote:


            On 29-08-2015, at 8:13 AM, Herbert König [hidden email] wrote:

                  Hi,

                  how do I go about reading a raw RGB 888 (24 bits deep output from raspiyuv) file into a Form?


            Well we need to understand the file format first to decode it and so far as some quick googling tells me the yuv files are
            completely raw; no header to tell us anything, just a long list of bytes. Since you can control the width and height of
            the image the camera takes (apparently, though it looks like it gets rounded up to 32 pixels in width and 16 in height?) I
            guess we can at least in principle assume the w & d for the data. The RGB888 is pretty much the Squeak pixels format for
            32bpp anyway so there shouldn’t be too much of a problem.

            Basically
            take your picture and write to file
            open file as binary in Squeak `myFileStream := (FileStream readOnlyFileNamed: ‘my.yuv’) binary`
            create a Form of appropriate size & depth  `myForm := Form extent: width@height depth: 32`
            read bytes from the filestream and stick them in the form’s bits array. There will be issues of byte-endianness to get
            right (squeak bitmaps are for some demented reason big-endian and I’d guess the pi YUV files are little-endian) and you’ll
            have to fill in the top (or bottom, see endianness) byte to set the alpha correctly.

            It’ll be something along the lines of checking the sizes match up, reading the data into the form’s bits array and making
            sure the bits all line up.

            Here’s a quick example from my pi2, since it tickled my curiousity

            in terminal - `raspiyuv -w 320 -h 208 -rgb -o smple.yuv`
            in Squeak
            Form extent: 320@208 depth: 32 -> inspect it
            in the inspector -
            |myfile alpha|
            myfile := FileStream readOnlyFileNamed: ‘/home/pi/sample.yuv’.
            myfile binary.
            bits size * 3 = myfile size ifFalse:[^nil].
            alpha := 16rFF<<24.
            1 to: bits size do: [ :i| |val|
            val := myfile next.
            val := val <<8 + myfile next.
            val := val <<8 + myfile next.
            val := alpha bitOr: val.
            bits at: i put: val].
            myfile close
            self display

            I get a pretty decent image displayed. Takes 250 mSec to read in on my pi2 with a cog-spur squeak. A bit over half that is
            the cost of using the largeinteger ‘alpha’ to set the proper alpha value for each pixel. You *can* leave that out if
            you’re going to simply do ‘myform display’ since the raw bitblt ignores the alpha. If you are going to be examining the
            pixels as just rgb values, save the time - I see 120mS in that case.


            Obviously once you have the general format sorted it ought to get moved into Form and tidied up as From
            class>>readRGBFromFileNamed: or similar.


            tim
            --
            tim Rowledge; [hidden email]; http://www.rowledge.org/tim
            Useful random insult:- If you give him a penny for his thoughts, you get change back.