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authorSolomon Peachy <pizza@shaftnet.org>2018-01-03 21:00:57 -0500
committerSolomon Peachy <pizza@shaftnet.org>2018-01-03 21:00:57 -0500
commit719dcaefe09ecf538546a54cc8e0a9646f7cb17e (patch)
tree2ccecb238a342009c19c1df401ada42d14bac82c
parentf7da653d715263277e22c2bbc2e895818c9fce95 (diff)
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magicard: Implement gamma correction.
The output looks pretty decent now!
-rw-r--r--backend_magicard.c79
1 files changed, 74 insertions, 5 deletions
diff --git a/backend_magicard.c b/backend_magicard.c
index 150ebd3..6a60d8a 100644
--- a/backend_magicard.c
+++ b/backend_magicard.c
@@ -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.