kopia lustrzana https://gitlab.com/sane-project/backends
calibration and gamma correction enhancements by M.Reinelt <reinelt@eunet.at>
Nathaniel Rutman
rodzic
79871a2b79
commit
b1d4dce599
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@ -57,6 +57,7 @@
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#include <string.h>
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#include <unistd.h> /* usleep */
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#include <time.h>
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#include <math.h> /* exp() */
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#ifdef HAVE_OS2_H
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#include <sys/types.h> /* mode_t */
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#endif
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@ -454,6 +455,7 @@ typedef struct CANON_Handle
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FILE *fp; /* output file pointer (for reading) */
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char *buf, *ptr; /* data buffer */
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unsigned char gain; /* static analog gain, 0 - 31 */
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double gamma; /* gamma correction */
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int flags;
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#define FLG_GRAY 0x01 /* grayscale */
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#define FLG_FORCE_CAL 0x02 /* force calibration */
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@ -975,14 +977,14 @@ plugin_cal (CANON_Handle * s)
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static SANE_Status
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compute_ogn (char *calfilename)
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{
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byte *linebuf, *oldline, *newline;
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mode_t oldmask;
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FILE *fp;
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int width, height, nlines = 0, region = -1, i, transition = 1, badcnt;
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int pct;
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int reglines[NREGIONS];
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byte *linebuf, *oldline, *newline;
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float *avg;
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float pct;
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float max_range[3], tmp1, tmp2;
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mode_t oldmask;
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fp = fopen (calfilename, "r");
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if (!fp)
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@ -1014,11 +1016,13 @@ compute_ogn (char *calfilename)
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badcnt = 0;
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for (i = 0; i < width; i++)
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{
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/* percentage change */
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pct = newline[i] - oldline[i];
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pct = ((pct < 0) ? -pct : pct) / newline[i];
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/* count pixels that have changed by 10% */
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if (pct > 0.10)
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/* Fix by M.Reinelt <reinelt@eunet.at>
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* do NOT use 10% (think of a dark area with
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* oldline=4 and newline=5, which is a change of 20% !!
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* Use an absolute difference of 10 as criteria
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*/
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if (pct < -10 || pct > 10)
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{
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badcnt++;
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DBG (16, "pix%d[%d/%d] ", i, newline[i], oldline[i]);
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@ -1122,11 +1126,18 @@ compute_ogn (char *calfilename)
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/* Gain multiplier:
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255 : 1.5 times brighter
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511 : 2 times brighter
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1023: 3 times brighter
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So - why did I choose 512 here? I forgot. */
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gain = 512 * ((max_range[i / (width / 3)] /
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(avg[i + width] - avg[i])) - 1);
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offset = avg[i];
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1023: 3 times brighter */
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/* Enhanced offset and gain calculation by M.Reinelt <reinelt@eunet.at>
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* These expressions were found by an iterative calibration process,
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* by changing gain and offset values for every pixel until the desired
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* values for black and white were reached, and finding an approximation
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* formula.
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* Note that offset is linear, but gain isn't!
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*/
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offset=(double)3.53*avg[i]-125;
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gain=(double)3861.0*exp(-0.0168*(avg[i+width]-avg[i]));
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DBG (14, "%d wht=%f blk=%f diff=%f gain=%d\n", i,
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avg[i + width], avg[i], avg[i + width] - avg[i], gain);
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/* 10-bit gain, 6-bit offset (subtractor) in two bytes */
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@ -1251,10 +1262,12 @@ scan (CANON_Handle * opt)
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write_byte (fd, COMMAND, 0x01);
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read_byte (fd, STATUS, &result); /* wants 0c */
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/* use linear gamma for now */
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/* create gamma table */
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buf = malloc (0x400);
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for (temp = 0; temp < 0x0400; temp++)
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buf[temp] = temp / 4;
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/* gamma calculation by M.Reinelt <reinelt@eunet.at> */
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buf[temp] = (double) 255.0 * exp(log((temp+0.5)/1023.0)/opt->gamma) + 0.5;
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/* Gamma R, write and verify */
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write_byte (fd, DATAPORT_TARGET, DP_R | DP_GAMMA);
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write_word (fd, DATAPORT_ADDR, DP_WRITE);
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@ -1406,12 +1419,13 @@ CANON_set_scan_parameters (CANON_Handle * scan,
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const int left,
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const int top,
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const int right,
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const int bottom, const int res, const int gain)
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const int bottom, const int res, const int gain, const double gamma)
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{
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DBG (2, "CANON_set_scan_parameters:\n");
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DBG (2, "gray = %d (ignored)\n", gray);
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DBG (2, "res = %d\n", res);
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DBG (2, "gain = %d\n", gain);
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DBG (2, "gamma = %f\n", gamma);
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DBG (2, "in 600dpi pixels:\n");
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DBG (2, "left = %d, top = %d\n", left, top);
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DBG (2, "right = %d, bottom = %d\n", right, bottom);
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@ -1433,12 +1447,16 @@ CANON_set_scan_parameters (CANON_Handle * scan,
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if ((gain < 0) || (gain > 64))
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return SANE_STATUS_INVAL;
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if (gamma <= 0.0)
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return SANE_STATUS_INVAL;
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scan->resolution = res;
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scan->x1 = left;
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scan->x2 = right - /* subtract 1 pixel */ 600 / scan->resolution;
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scan->y1 = top;
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scan->y2 = bottom;
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scan->gain = gain;
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scan->gamma = gamma;
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scan->flags = 0;
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return SANE_STATUS_GOOD;
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@ -252,7 +252,7 @@ static SANE_Int optionAGainValue = 1;
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static SANE_Option_Descriptor optionAGainDescriptor = {
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SANE_I18N ("gain"),
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SANE_I18N ("Analog gain"),
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SANE_I18N ("Analog Gain"),
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SANE_I18N ("Increase or decrease the analog gain of the CCD array"),
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SANE_TYPE_INT,
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SANE_UNIT_NONE,
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@ -287,6 +287,46 @@ optionAGainCallback (SANE_Option * option, SANE_Handle handle,
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}
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static SANE_Fixed optionGammaValue = SANE_FIX (1.6);
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static SANE_Option_Descriptor optionGammaDescriptor = {
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SANE_I18N ("gamma"),
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SANE_I18N ("Gamma Correction"),
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SANE_I18N ("Selects the gamma corrected transfer curve"),
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SANE_TYPE_FIXED,
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SANE_UNIT_NONE,
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sizeof (SANE_Int),
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SANE_CAP_SOFT_SELECT | SANE_CAP_SOFT_DETECT | SANE_CAP_ADVANCED,
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SANE_CONSTRAINT_NONE,
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{NULL}
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};
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static SANE_Status
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optionGammaCallback (SANE_Option * option, SANE_Handle handle,
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SANE_Action action, void *value, SANE_Int * info)
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{
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option = option;
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handle = handle;
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info = info; /* Eliminate warning about unused parameters */
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switch (action)
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{
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case SANE_ACTION_SET_AUTO:
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return SANE_STATUS_INVAL;
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break;
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case SANE_ACTION_SET_VALUE:
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optionGammaValue = *(SANE_Fixed *) value;
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*info |= SANE_INFO_RELOAD_PARAMS;
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break;
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case SANE_ACTION_GET_VALUE:
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*(SANE_Fixed *) value = optionGammaValue;
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break;
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}
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return SANE_STATUS_GOOD;
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}
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/*
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Scan range
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*/
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@ -490,6 +530,7 @@ static SANE_Option so[] = {
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{&optionGrayscaleDescriptor, optionGrayscaleCallback},
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#endif
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{&optionAGainDescriptor, optionAGainCallback},
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{&optionGammaDescriptor, optionGammaCallback},
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{&optionTopLeftXDescriptor, optionTopLeftXCallback},
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{&optionTopLeftYDescriptor, optionTopLeftYCallback},
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{&optionBotRightXDescriptor, optionBotRightXCallback},
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@ -899,7 +940,8 @@ sane_start (SANE_Handle handle)
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MM_IN_INCH * 600,
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SANE_UNFIX (optionBotRightYValue) /
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MM_IN_INCH * 600,
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optionResolutionValue, optionAGainValue);
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optionResolutionValue, optionAGainValue,
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SANE_UNFIX (optionGammaValue));
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if (res != SANE_STATUS_GOOD)
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return res;
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