/*************************************************************************** * This file is a part of CADS/UVS fits2jpeg conversion software * * Copyright (C) 2012 by CADS/UV Software Team, * * Indian Institute of Astrophysics * * Bangalore 560034 * * cads_AT_iiap.res.in * * * * This program is free software; you can redistribute it and/or modify * * it under the terms of the GNU General Public License as published by * * the Free Software Foundation; either version 2 of the License, or * * (at your option) any later version. * * * * This program is distributed in the hope that it will be useful, * * but WITHOUT ANY WARRANTY; without even the implied warranty of * * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * * GNU General Public License for more details. * * * * You should have received a copy of the GNU General Public License * * along with this program; if not, write to the * * Free Software Foundation, Inc., * * 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. * ***************************************************************************/ /*Header Definitions*/ #include "fits2jpeg.h" /*---------------------------------------------------------------------------* * SCALE_PIXELS: Changes the pixel scale to linear/log/sqroot/etc.. *---------------------------------------------------------------------------*/ void scale_pixels(int scale, unsigned int npixels, float *data, JSAMPLE *image_buffer) { unsigned int i = 0; int JMAXVAL = 255; float datamax = 0.0, datamin = 0.0, tmp = 0.0; float hist[256] = {0.0}, cumhist[256] = {0.0}; float scl_data = 0.0; /* first find min & max in data */ datamax = -1.0 * FLT_MAX; datamin = FLT_MAX; for (i = 0; i < npixels; ++i) { if (data[i] > datamax) datamax = data[i]; if (data[i] < datamin) datamin = data[i]; } /*endfor*/ /* Convert data into bytscaled values for jpeg file */ /* the dynamic range is reduced to 255 for jpeg */ scl_data = (datamax - datamin)/(float)JMAXVAL; for (i = 0; i < npixels; ++i) data[i] = (data[i] - datamin)/scl_data; /* All data is now squeezed into the range 0 - 255 */ /* NOTE: At this point onwards min & max is 0 and 255 respectively */ datamax = (float)JMAXVAL; datamin = 0.0; /* initialize image histogram. ensure all are zeroes in hist[] */ /*-----------------------------------------------------------------------*/ for (i = 0; i <= JMAXVAL; ++i) hist[i] = 0; /* construct the image histogram */ tmp = 1.0/(float)npixels; for (i = 0; i <= npixels; ++i) hist[(int)floor(data[i])] += tmp; /* And the cumulative histogram */ cumhist[0] = hist[0]; for (i = 1; i <= JMAXVAL; ++i) cumhist[i] += cumhist[i - 1] + hist[i]; /* Linear scale (min-max) : This is the default scaling * histo-eq will fail if we dont generate image_buffer here */ for (i = 0; i < npixels; ++i) image_buffer[i] = (int)(data[i]); /*-----------------------------------------------------------------------*/ switch (scale) { case 1 : /* Square root */ printinfo("Using square-root scale"); scl_data = sqrt((float)JMAXVAL)/(float)JMAXVAL; for (i = 0; i < npixels; ++i) image_buffer[i] = (int)(sqrt(data[i])/scl_data); break; case 2 : /* Square */ printinfo("Using quadratic scale"); scl_data = pow((float)JMAXVAL,2)/(float)JMAXVAL; for (i = 0; i < npixels; ++i) image_buffer[i] = (int)abs((pow(data[i],2) - 1.0)/scl_data); break; case 3 : /* Cubic */ printinfo("Using cubic scale"); scl_data = pow((float)JMAXVAL,3)/(float)JMAXVAL; for (i = 0; i < npixels; ++i) image_buffer[i] = (int)abs((pow(data[i],3) - 1.0)/scl_data); break; case 4 : /* log */ printinfo("Using log scale"); scl_data = log(1.0 + (float)JMAXVAL)/(float)JMAXVAL; for (i = 0; i < npixels; ++i) image_buffer[i] = (int)((log(abs(data[i]) + 1.0))/scl_data); break; case 5 : /* contrast stretch */ printinfo("Performing histogram stretch (normalization)"); /* We need to go through the cumulative histogram to pick the * appropriate values for datamin and datamax */ i = 0; while (i < JMAXVAL) { if (cumhist[i] >= 0.01) { datamin = (float) i; break; } i++; } i = JMAXVAL; while (i > 0) { if (cumhist[i] <= 0.99) { datamax = (float) i; break; } i--; } scl_data = (datamax - datamin)/(float)JMAXVAL; for (i = 0; i < npixels; ++i) { if (image_buffer[i] >= datamax) image_buffer[i] = JMAXVAL; else if (image_buffer[i] <= datamin) image_buffer[i] = 0; else image_buffer[i] = (int) abs((image_buffer[i] - datamin)/scl_data); } break; case 6 : /* histogram equalization */ printinfo("Performing Histogram Equalization"); for (i = 0; i < npixels; ++i) image_buffer[i] = cumhist[image_buffer[i]] * JMAXVAL; break; default : printinfo("Using linear scale"); break; } } /*---------------------------------------------------------------------------* * RESIZE_IMAGE: Scales down/up the image_buffer *---------------------------------------------------------------------------*/ void resize_image(long *xdim, long *ydim, float zoomfact, JSAMPLE *image_buffer) { int offset = 0, index = 0; int A, B, C, D, x, y, gray; JSAMPLE *buff; unsigned int i = 0, j = 0; unsigned long npixels = 0; long w = *xdim, h = *ydim; long zxdim = 0, zydim = 0; float xdiff, ydiff, xratio, yratio; zxdim = (int)(w * zoomfact); zydim = (int)(h * zoomfact); npixels= zxdim * zydim; xratio = ((float)(w - 1))/zxdim; yratio = ((float)(h - 1))/zydim; /* allocate space for *buff */ buff = (unsigned char *) malloc(sizeof(char) * zxdim * zydim); index = 0; offset = 0; for (i = 0; i < zydim; i++) { y = (int)(yratio * i); ydiff = (yratio * i) - y; for (j = 0; j < zxdim; j++) { x = (int)(xratio * j); xdiff = (xratio * j) - x; index = y * w + x; A = image_buffer[index] & 0xff; B = image_buffer[index + 1] & 0xff; C = image_buffer[index + w] & 0xff; D = image_buffer[index + w + 1] & 0xff; gray = (int)(A * (1 - xdiff) * (1 - ydiff) + B * (xdiff) * (1 - ydiff) + C * (ydiff) * (1 - xdiff) + D * (xdiff) * (ydiff) ); buff[offset++] = gray; } } *xdim = zxdim; *ydim = zydim; image_buffer = realloc(image_buffer, sizeof(char) * npixels); if (!image_buffer) printerro("Failed to allocate memory"); for (i = 0; i < npixels; ++i) image_buffer[i] = buff[i]; }