Decoding bmp ?

[antonius]

Posted on April 11, 2014 at 11:21

Guys,

Does anyone of you have experience on decoding bmp ? I want to display bmp file to my LCD... Any clues ? thanks #i-have-a-clue

[antonius]

Posted on April 21, 2014 at 06:13

So if I follow :

http://upload.wikimedia.org/wikipedia/commons/thumb/a/a7/Bilin3.png/220px-Bilin3.png from http://en.wikipedia.org/wiki/Bilinear_interpolation#Application_in_image_processing I will shring the picture by half ? for example 1024 x 768 becoming 512 x 384 ?

[antonius]

Posted on April 21, 2014 at 07:28

I have test6.bmp which is 2x2 pixel 24 bits:

Is offset 0x36 which value = 0xC0 equal to coordinate 0,0 (red color) ? Red color is defined from 0x36 until 0x38 ? ==> 0xC0,0x40,0x40, then (0,1) green color 0x00,0xFF,0xFF, then (1,0),blue color = 0x82,0x04,0x40,then (1,1) yellow color = 0x20, 0xE0,0x40 and then following :

[antonius]

Posted on April 22, 2014 at 02:17

Am I on the right calculation and way of thinking ?

thanks

[antonius]

Posted on April 22, 2014 at 02:30

Does it always begin from offset 0x3E on the file no matter the resolution of the picture ?

It's the same for 1bit,8bits,16bits and 24bits picture ? I can see from every pictures, it's started from 0x36, reference :

Start of pixel array (bitmap data)

36h 3

00 00 FF

0 0 255 Red, Pixel (0,1)

http://en.wikipedia.org/wiki/BMP_file_format#Bitmap_file_header

Thanks

[antonius]

Posted on April 27, 2014 at 06:36

I tried this code :

//262K picture

uint16_t destx;

uint16_t desty;


delay_ms(1500);

LCD_Clear(Black); 

res = f_open(&fsrc, filename, FA_READ);


f_read(&fsrc, hdr_256, 
sizeof
(hdr_256),&bytesread); 
// Read header

off = *((uint32_t *)&hdr_256[0x0A]); 
// offset to rasters


sourcewidth = *((uint32_t *)&hdr_256[0x12]); 
// X pixels

sourceheight = *((uint32_t *)&hdr_256[0x16]); 
// Y pixels



f_lseek(&fsrc, off); 
// Seek to the data

destx = 0;

desty = 0;

for
(y = 0, ny = 0; y < sourceheight; ny += 3, ny++)


{

if
(ny == 5)

{

y++;

ny = 0;

}

for
(x = 0,nx = 0; x < sourcewidth; x += 3,nx++)

{

uint32_t rgb;

if
(nx == 5)

{

x++;

nx = 0;

}

f_read(&fsrc, &rgb, 3, &bytesread); 
// Read pixel B G R

// RRRRRRRRGGGGGGGGBBBBBBBB 8:8:8

// RRRRRGGGGGGBBBBB 5:6:5

rgb = ((rgb & 0xF80000) >> 8) | ((rgb & 0x00FC00) >> 5) | ((rgb & 0x0000F8) >> 3);

LCD_SetPoint(desty, destx, rgb);

destx++;

if
(destx == 320)

{

destx = 0;

desty++;

}

}

}

f_close(&fsrc);

delay_ms(2000);

for displaying :

http://iphotobucket.com/albums/p231/picture_77/test32_zpsa24eb6e1.png

http://iphotobucket.com/albums/p231/picture_77/test32_zpsa24eb6e1.png

but it's displaying :

http://iphotobucket.com/albums/p231/picture_77/IMG_20140427_095513_zpsd8864b8e.jpg

Does anyone have a clue ? thanks

[Tesla DeLorean]

Posted on April 27, 2014 at 18:40

Yes, the logic there seems rather broken, and the PNG won't be handled by BMP code

[antonius]

Posted on April 28, 2014 at 01:26

I'm not using *.png on my SD card, that's for sure, photo bucket convert it...

I tried this function

void LCD_BMP_reading_shrink_test(char filename[120])

{

char temp_buffer[100],line[512];

int count,z,bmpData,bmpAddr;

int x = 0;

int i,y = 0;

int xx, yy,ny,nx;

uint8_t hdr[0x28];

UINT bytesread;

uint8_t hdr_256[0x36];

static uint16_t w[256];

uint32_t off,sourcewidth,sourceheight,pixeloff;


//262K picture

uint16_t destx;

uint16_t desty;


delay_ms(1500);

LCD_Clear(Black); 

res = f_open(&fsrc, filename, FA_READ);


f_read(&fsrc, hdr_256, sizeof(hdr_256),&bytesread); // Read header

off = *((uint32_t *)&hdr_256[0x0A]); // offset to rasters


sourcewidth = *((uint32_t *)&hdr_256[0x12]); // X pixels

sourceheight = *((uint32_t *)&hdr_256[0x16]); // Y pixels


pixeloff = off + (y * 1024 * 3) + (x * 3); // Assuming three bytes per pixel

//f_lseek(&fsrc, pixeloff); // Seek to the desired pixel 

f_lseek(&fsrc, off); // Seek to the data


destx = 0;

desty = 0;

//for(y = 0, ny = 0; y < 
sourceheight
; ny += 3, ny++)

for(
y
= 
0
, 
ny
= 
0
; y < sourceheight; y += 3, ny++)


{

if (ny == 5)

{

y++;

ny
= 
0
;

}


for(
x
= 
0
,
nx
= 
0
; x < sourcewidth; x += 3,nx++)

{

uint32_t rgb;

if (nx == 5)

{

x++;

nx
= 
0
;

}

f_read(&fsrc, &rgb, 3, &bytesread); // Read pixel B G R

// RRRRRRRRGGGGGGGGBBBBBBBB 8:8:8

// RRRRRGGGGGGBBBBB 5:6:5

rgb = ((rgb & 0xF80000) >> 8) | ((rgb & 0x00FC00) >> 5) | ((rgb & 0x0000F8) >> 3);

LCD_SetPoint(desty, destx, rgb);




destx++;

if(destx == 320)

{

destx = 0;

desty++;

}

}

}

f_close(&fsrc);

delay_ms(2000);


}

I want to convert 1024*768 :

http://iphotobucket.com/albums/p231/picture_77/test32_zpsa24eb6e1.png

The result I got from that function :

http://iphotobucket.com/albums/p231/picture_77/IMG_20140427_095513_zpsd8864b8e.jpg

Do you have idea where I miss here ? thanks

[antonius]

Posted on April 28, 2014 at 13:06

I was trying to display

but I got like this on LCD : The code I used :

int
count,z,bmpData,bmpAddr;

int
x = 0;

int
i,y = 0;

int
xx, yy,ny,nx;

uint8_t hdr[0x28];

UINT
bytesread;

uint8_t hdr_256[0x36];

static
uint16_t w[256];

uint32_t off,sourcewidth,sourceheight,pixeloff;


//262K picture

uint16_t destx;

uint16_t desty;


delay_ms(1500);

LCD_Clear(Black); 

res = f_open(&fsrc, filename, FA_READ);


f_read(&fsrc, hdr_256, 
sizeof
(hdr_256),&bytesread); 
// Read header

off = *((uint32_t *)&hdr_256[0x0A]); 
// offset to rasters


sourcewidth = *((uint32_t *)&hdr_256[0x12]); 
// X pixels

sourceheight = *((uint32_t *)&hdr_256[0x16]); 
// Y pixels




destx = 0;

desty = 0;

//for(y = 0, ny = 0; y < sourceheight; ny += 3, ny++)

for
(y = 0, ny = 0; y < sourceheight; y += 3, ny++)


{

if
(ny == 5)

{

y++;

ny = 0; 

}


for
(x = 0,nx = 0; x < sourcewidth; x += 3,nx++)

{

uint32_t rgb;

if
(nx == 5)

{

x++;

nx = 0;

}

pixeloff = off + (y * 1024 * 3) + (x * 3); 
// Assuming three bytes per pixel

f_lseek(&fsrc, pixeloff); 
// Seek to the desired pixel 

//f_lseek(&fsrc, off); // Seek to the data

f_read(&fsrc, &rgb, 3, &bytesread); 
// Read pixel B G R

// RRRRRRRRGGGGGGGGBBBBBBBB 8:8:8

// RRRRRGGGGGGBBBBB 5:6:5

rgb = ((rgb & 0xF80000) >> 8) | ((rgb & 0x00FC00) >> 5) | ((rgb & 0x0000F8) >> 3);

LCD_SetPoint(desty, destx, rgb);

//sprintf(temp_buffer,''%.2d'',rgb);printf(temp_buffer);printf(''
'');



destx++;

if
(destx == 320)

{

destx = 0;

desty++;

}

}

}

f_close(&fsrc);

delay_ms(2000);

Any clues ? thanks

[Tesla DeLorean]

Posted on April 28, 2014 at 14:27

int count,z,bmpData,bmpAddr;
int x = 0;
int i,y = 0;
int xx, yy;
uint8_t hdr[0x28];
UINT bytesread;
uint8_t hdr_256[0x36];
static uint16_t w[256];
uint32_t off,sourcewidth,sourceheight,pixeloff;
//262K picture
delay_ms(1500);
LCD_Clear(Black);
res = f_open(&fsrc, filename, FA_READ);
f_read(&fsrc, hdr_256, sizeof(hdr_256),&bytesread); // Read header
off = *((uint32_t *)&hdr_256[0x0A]); // offset to rasters
sourcewidth = *((uint32_t *)&hdr_256[0x12]); // X pixels
sourceheight = *((uint32_t *)&hdr_256[0x16]); // Y pixels
for(y = 0; y < 
sourceheight
; y += 3)
{
for(
x
= 
0
; x < sourcewidth; x += 3)
{
pixeloff
= off + (((y * sourcewidth) + x) * 3); // Assuming three bytes per pixel
f_lseek(&fsrc, pixeloff); // Seek to the desired pixel
f_read(&fsrc, &rgb, 3, &bytesread); // Read pixel B G R
// RRRRRRRRGGGGGGGGBBBBBBBB 8:8:8
// RRRRRGGGGGGBBBBB 5:6:5
rgb = ((rgb & 0xF80000) >> 8) | ((rgb & 0x00FC00) >> 5) | ((rgb & 0x0000F8) >> 3);
LCD_SetPoint(y/3, x/3, rgb);
}
}
f_close(&fsrc);
delay_ms(2000);

[antonius]

Posted on April 28, 2014 at 14:38

It does the task but why can't I see the white color ? suppose to be blue and white,

but on LCD blue and dot dot white not complete white ? Have a look... Thanks