magicard: Implement gamma correction.

The output looks pretty decent now!
This commit is contained in:
Solomon Peachy 2018-01-03 21:00:57 -05:00
parent 8d74305b7e
commit faa672e9c2
1 changed files with 74 additions and 5 deletions

View File

@ -47,6 +47,66 @@
#define USB_VID_MAGICARD 0x0C1F
#define USB_PID_MAGICARD_TANGO2E 0x1800
/* Gamma tables computed with this perl program:
my $input_bpp = 8;
my $output_bpp = 6;
my $gamma = 1/1.8; # or 1/2.2 or whatever.
my $i;
for (my $i = 0 ; $i < (2 ** $input_bpp) ; $i++) {
my $linear = $i / (2 ** $input_bpp);
my $gc = ($linear ** $gamma) * (2 ** $output_bpp);
$gc = int($gc);
print "$gc, ";
}
*/
static uint8_t gammas[2][256] = {
/* Gamma = 2.2 */
{
0, 5, 7, 8, 9, 10, 11, 12, 13, 13, 14, 15, 15, 16, 17,
17, 18, 18, 19, 19, 20, 20, 20, 21, 21, 22, 22, 23, 23, 23,
24, 24, 24, 25, 25, 25, 26, 26, 26, 27, 27, 27, 28, 28, 28,
29, 29, 29, 29, 30, 30, 30, 31, 31, 31, 31, 32, 32, 32, 32,
33, 33, 33, 33, 34, 34, 34, 34, 35, 35, 35, 35, 35, 36, 36,
36, 36, 37, 37, 37, 37, 37, 38, 38, 38, 38, 38, 39, 39, 39,
39, 39, 40, 40, 40, 40, 40, 41, 41, 41, 41, 41, 42, 42, 42,
42, 42, 43, 43, 43, 43, 43, 43, 44, 44, 44, 44, 44, 45, 45,
45, 45, 45, 45, 46, 46, 46, 46, 46, 46, 47, 47, 47, 47, 47,
47, 48, 48, 48, 48, 48, 48, 48, 49, 49, 49, 49, 49, 49, 50,
50, 50, 50, 50, 50, 50, 51, 51, 51, 51, 51, 51, 51, 52, 52,
52, 52, 52, 52, 52, 53, 53, 53, 53, 53, 53, 53, 54, 54, 54,
54, 54, 54, 54, 55, 55, 55, 55, 55, 55, 55, 56, 56, 56, 56,
56, 56, 56, 56, 57, 57, 57, 57, 57, 57, 57, 57, 58, 58, 58,
58, 58, 58, 58, 58, 59, 59, 59, 59, 59, 59, 59, 59, 60, 60,
60, 60, 60, 60, 60, 60, 61, 61, 61, 61, 61, 61, 61, 61, 62,
62, 62, 62, 62, 62, 62, 62, 62, 63, 63, 63, 63, 63, 63, 63, 63,
},
/* Gamma = 1.8 */
{
0, 2, 4, 5, 6, 7, 7, 8, 9, 9, 10, 11, 11, 12, 12,
13, 13, 14, 14, 15, 15, 15, 16, 16, 17, 17, 17, 18, 18, 19,
19, 19, 20, 20, 20, 21, 21, 21, 22, 22, 22, 23, 23, 23, 24,
24, 24, 24, 25, 25, 25, 26, 26, 26, 26, 27, 27, 27, 28, 28,
28, 28, 29, 29, 29, 29, 30, 30, 30, 30, 31, 31, 31, 31, 32,
32, 32, 32, 33, 33, 33, 33, 34, 34, 34, 34, 34, 35, 35, 35,
35, 36, 36, 36, 36, 36, 37, 37, 37, 37, 37, 38, 38, 38, 38,
39, 39, 39, 39, 39, 40, 40, 40, 40, 40, 41, 41, 41, 41, 41,
42, 42, 42, 42, 42, 42, 43, 43, 43, 43, 43, 44, 44, 44, 44,
44, 45, 45, 45, 45, 45, 45, 46, 46, 46, 46, 46, 47, 47, 47,
47, 47, 47, 48, 48, 48, 48, 48, 48, 49, 49, 49, 49, 49, 49,
50, 50, 50, 50, 50, 50, 51, 51, 51, 51, 51, 51, 52, 52, 52,
52, 52, 52, 53, 53, 53, 53, 53, 53, 54, 54, 54, 54, 54, 54,
55, 55, 55, 55, 55, 55, 55, 56, 56, 56, 56, 56, 56, 57, 57,
57, 57, 57, 57, 57, 58, 58, 58, 58, 58, 58, 58, 59, 59, 59,
59, 59, 59, 60, 60, 60, 60, 60, 60, 60, 61, 61, 61, 61, 61,
61, 61, 62, 62, 62, 62, 62, 62, 62, 63, 63, 63, 63, 63, 63, 63,
}
};
/* Private data structure */
struct magicard_ctx {
struct libusb_device_handle *dev;
@ -397,9 +457,18 @@ static void downscale_and_extract(int gamma, uint32_t pixels,
uint8_t b_shift;
/* Downscale color planes from 8bpp -> 6bpp; */
y = *y_i++ >> 2;
m = *m_i++ >> 2;
c = *c_i++ >> 2;
if (gamma) {
if (gamma > 2)
gamma = 2;
gamma--;
y = gammas[gamma][*y_i++];
m = gammas[gamma][*m_i++];
c = gammas[gamma][*c_i++];
} else {
y = *y_i++ >> 2;
m = *m_i++ >> 2;
c = *c_i++ >> 2;
}
/* Extract "true black" from ymc data, if enabled */
if (k_o && y == 0x3f && m == 0x3f && c == 0x3f) {
@ -763,7 +832,7 @@ static int magicard_cmdline_arg(void *vctx, int argc, char **argv)
struct dyesub_backend magicard_backend = {
.name = "Magicard family",
.version = "0.07",
.version = "0.08",
.uri_prefix = "magicard",
.cmdline_arg = magicard_cmdline_arg,
.cmdline_usage = magicard_cmdline,
@ -913,7 +982,7 @@ struct dyesub_backend magicard_backend = {
Commands consumed by backend:
ICC%d Gamma curve (0, 1, 2) -- NOT IMPLEMENTED YET
ICC%d Gamma curve (0, 1, 2) -- off, 2.2, or 1.8 respectively.
X-GP-8 Raw data is 8bpp. needs to be converted.
X-GP-RK Extract K channel from color data.