kopia lustrzana https://gitlab.com/sane-project/backends
gl847 shading calibration refactor
Stphane Voltz
rodzic
55d5ef6fd9
commit
adc2060579
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@ -2958,6 +2958,165 @@ compute_coefficient (unsigned int coeff, unsigned int target, unsigned int value
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return result;
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}
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/** @brief compute shading coefficients for LiDE scanners
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*
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The dark/white shading is actually performed _after_ reducing
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resolution via averaging. only dark/white shading data for what would be
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first pixel at full resolution is used.
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scanner raw input to output value calculation:
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o=(i-off)*(gain/coeff)
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from datasheet:
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off=dark_average
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gain=coeff*bright_target/(bright_average-dark_average)
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works for dark_target==0
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what we want is these:
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bright_target=(bright_average-off)*(gain/coeff)
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dark_target=(dark_average-off)*(gain/coeff)
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leading to
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off = (dark_average*bright_target - bright_average*dark_target)/(bright_target - dark_target)
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gain = (bright_target - dark_target)/(bright_average - dark_average)*coeff
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*
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* @param dev scanner's device
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* @param shading_data memory area where to store the computed shading coefficients
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* @param pixels_per_line number of pixels per line
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* @param words_per_color memory words per color channel
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* @param channels number of color channels (actually 1 or 3)
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* @param o shading coefficients left offset
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* @param coeff 4000h or 2000h depending on fast scan mode or not (GAIN4 bit)
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* @param target_bright value of the white target code
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* @param target_dark value of the black target code
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*/
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#ifndef UNIT_TESTING
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static
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#endif
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void
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compute_averaged_planar (Genesys_Device * dev,
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uint8_t * shading_data,
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unsigned int pixels_per_line,
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unsigned int words_per_color,
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unsigned int channels,
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unsigned int o,
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unsigned int coeff,
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unsigned int target_bright,
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unsigned int target_dark)
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{
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unsigned int x, i, j, br, dk, res, avgpixels, val;
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/* initialize result */
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/* memset (shading_data, 0xff, words_per_color * 3 * 2); */
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/* duplicate half-ccd logic */
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res = dev->settings.xres;
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if ((dev->model->flags & GENESYS_FLAG_HALF_CCD_MODE)
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&& dev->settings.xres <= dev->sensor.optical_res / 2)
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{
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/* scanner is using half-ccd mode */
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res *= 2;
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}
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/*this should be evenly dividable */
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avgpixels = dev->sensor.optical_res / res;
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/* gl841 and gl847 supports 1/1 1/2 1/3 1/4 1/5 1/6 1/8 1/10 1/12 1/15 averaging */
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if (avgpixels < 1)
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avgpixels = 1;
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else if (avgpixels < 6)
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avgpixels = avgpixels;
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else if (avgpixels < 8)
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avgpixels = 6;
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else if (avgpixels < 10)
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avgpixels = 8;
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else if (avgpixels < 12)
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avgpixels = 10;
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else if (avgpixels < 15)
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avgpixels = 12;
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else
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avgpixels = 15;
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DBG (DBG_info, "compute_planar_averaged: averaging over %d pixels\n",
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avgpixels);
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for (x = 0; x <= pixels_per_line - avgpixels; x += avgpixels)
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{
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if ((x + o) * 2 * 2 + 3 > words_per_color * 2)
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break;
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for (j = 0; j < channels; j++)
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{
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dk = 0;
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br = 0;
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for (i = 0; i < avgpixels; i++)
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{
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/* dark data */
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dk += (dev->dark_average_data[(x + i + pixels_per_line * j) * 2]
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| (dev-> dark_average_data[(x + i + pixels_per_line * j) * 2 + 1] << 8));
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/* white data */
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br += (dev->white_average_data[(x + i + pixels_per_line * j) * 2]
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| (dev-> white_average_data[(x + i + pixels_per_line * j) * 2 + 1] << 8));
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}
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br /= avgpixels;
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dk /= avgpixels;
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if (br * target_dark > dk * target_bright)
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val = 0;
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else if (dk * target_bright - br * target_dark > 65535
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* (target_bright - target_dark))
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val = 65535;
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else
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val = (dk * target_bright - br * target_dark) / (target_bright
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- target_dark);
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/*fill all pixels, even if only the last one is relevant */
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for (i = 0; i < avgpixels; i++)
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{
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shading_data[(x + o + i) * 2 * 2 + words_per_color * 2 * j] = val & 0xff;
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shading_data[(x + o + i) * 2 * 2 + words_per_color * 2 * j + 1] = val >> 8;
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}
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val = br - dk;
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if (65535 * val > (target_bright - target_dark) * coeff)
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val = (coeff * (target_bright - target_dark)) / val;
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else
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val = 65535;
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/*fill all pixels, even if only the last one is relevant */
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for (i = 0; i < avgpixels; i++)
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{
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shading_data[(x + o + i) * 2 * 2 + words_per_color * 2 * j + 2] = val & 0xff;
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shading_data[(x + o + i) * 2 * 2 + words_per_color * 2 * j + 3] = val >> 8;
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}
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}
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/*fill remaining channels */
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for (j = channels; j < 3; j++)
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{
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for (i = 0; i < avgpixels; i++)
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{
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shading_data[(x + o + i) * 2 * 2 + words_per_color * 2 * j]
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= shading_data[(x + o + i) * 2 * 2 + words_per_color * 0];
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shading_data[(x + o + i) * 2 * 2 + words_per_color * 2 * j + 1]
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= shading_data[(x + o + i) * 2 * 2 + words_per_color
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* 2 * 0 + 1];
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shading_data[(x + o + i) * 2 * 2 + words_per_color * 2 * j + 2]
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= shading_data[(x + o + i) * 2 * 2 + words_per_color
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* 2 * 0 + 2];
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shading_data[(x + o + i) * 2 * 2 + words_per_color * 2 * j + 3]
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= shading_data[(x + o + i) * 2 * 2 + words_per_color
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* 2 * 0 + 3];
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}
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}
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}
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}
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/**
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* Computes shading coefficient using formula in data sheet. 16bit data values
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* manipulated here are little endian. For now we assume deletion scanning type
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@ -3305,9 +3464,19 @@ genesys_send_shading_coefficient (Genesys_Device * dev)
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coeff,
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target_code);
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break;
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case CCD_CANONLIDE35:
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case CIS_CANONLIDE100:
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case CIS_CANONLIDE200:
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compute_averaged_planar(dev,
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shading_data,
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pixels_per_line,
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words_per_color,
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channels,
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4,
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coeff,
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0xfa00,
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0x0a00);
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break;
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case CCD_CANONLIDE35:
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target_bright = 0xfa00;
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target_dark = 0xa00;
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o = 4; /*first four pixels are ignored */
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@ -5531,7 +5700,7 @@ init_gamma_vector_option (Genesys_Scanner * scanner, int option)
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* @param size maximum size of the range
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* @return a poiter to a valid range or NULL
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*/
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static create_range(SANE_Fixed size)
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static SANE_Range *create_range(SANE_Fixed size)
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{
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SANE_Range *range=NULL;
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@ -971,7 +971,7 @@ static Genesys_Model canon_lide_100_model = {
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| GENESYS_FLAG_DARK_CALIBRATION
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| GENESYS_FLAG_CUSTOM_GAMMA,
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GENESYS_HAS_SCAN_SW | GENESYS_HAS_COPY_SW | GENESYS_HAS_EMAIL_SW | GENESYS_HAS_FILE_SW,
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50,
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150,
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400
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};
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