6c48d6754c59c4a847efa4c7b26c3e09ef9ca44c
1 /***************************************************************************
2 * This file is a part of CADS/UVS fits2jpeg conversion software *
3 * Copyright (C) 2012 by CADS/UV Software Team, *
4 * Indian Institute of Astrophysics *
5 * Bangalore 560034 *
6 * cads_AT_iiap.res.in *
7 * *
8 * This program is free software; you can redistribute it and/or modify *
9 * it under the terms of the GNU General Public License as published by *
10 * the Free Software Foundation; either version 2 of the License, or *
11 * (at your option) any later version. *
12 * *
13 * This program is distributed in the hope that it will be useful, *
14 * but WITHOUT ANY WARRANTY; without even the implied warranty of *
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the *
16 * GNU General Public License for more details. *
17 * *
18 * You should have received a copy of the GNU General Public License *
19 * along with this program; if not, write to the *
20 * Free Software Foundation, Inc., *
21 * 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. *
22 ***************************************************************************/
24 /*Header Definitions*/
25 #include "fits2jpeg.h"
27 void read_fits(char * fits_file_name, long * xdim, long * ydim, float ** data)
28 {
29 fitsfile *fptr;
30 int status = 0, nfound, anynull;
31 long naxes[2];
32 long npixels;
33 float nullval = 0.0;
35 fits_open_file(&fptr, fits_file_name, READONLY, &status);
36 fits_read_keys_lng(fptr, "NAXIS", 1, 2, naxes, &nfound, &status);
37 if (status)
38 printerro(strcat(fits_file_name, " <-- Failed to open the file"));
40 /* Read in data */
41 npixels = naxes[0] * naxes[1];
42 (*data) = malloc(sizeof(float) * npixels);
44 nullval = 0;
45 if (fits_read_img(fptr, TFLOAT, 1, npixels, &nullval, (*data), &anynull,
46 &status))
47 printerro(strcat(fits_file_name, " has no valid fits image data"));
49 *xdim = naxes[0];
50 *ydim = naxes[1];
52 fits_close_file(fptr, &status);
53 }
55 /*---------------------------------------------------------------------------*
56 * SCALE_PIXELS: Changes the pixel scale to linear/log/sqroot/etc..
57 *---------------------------------------------------------------------------*/
58 void scale_pixels(int scale, unsigned int npixels, float *data,
59 JSAMPLE ** image_buffer)
60 {
61 unsigned int i = 0;
62 int JMAXVAL = 255;
63 float datamax = 0.0, datamin = 0.0, tmp = 0.0;
64 float hist[256] = {0.0}, cumhist[256] = {0.0};
65 float scl_data = 0.0;
68 /* first find min & max in data */
69 datamax = -1.0 * FLT_MAX;
70 datamin = FLT_MAX;
71 for (i = 0; i < npixels; ++i)
72 {
73 if (data[i] > datamax) datamax = data[i];
74 if (data[i] < datamin) datamin = data[i];
75 } /*endfor*/
78 /* Convert data into bytscaled values for jpeg file */
79 /* the dynamic range is reduced to 255 for jpeg */
80 scl_data = (datamax - datamin)/(float)JMAXVAL;
82 for (i = 0; i < npixels; ++i)
83 data[i] = (data[i] - datamin)/scl_data;
86 /* All data is now squeezed into the range 0 - 255 */
87 /* NOTE: At this point onwards min & max is 0 and 255 respectively */
88 datamax = (float)JMAXVAL;
89 datamin = 0.0;
91 /* initialize image histogram. ensure all are zeroes in hist[] */
92 /*-----------------------------------------------------------------------*/
93 for (i = 0; i <= JMAXVAL; ++i) hist[i] = 0;
95 /* construct the image histogram */
96 tmp = 1.0/(float)npixels;
97 for (i = 0; i <= npixels; ++i)
98 hist[(int)floor(data[i])] += tmp;
100 /* And the cumulative histogram */
101 cumhist[0] = hist[0];
102 for (i = 1; i <= JMAXVAL; ++i)
103 cumhist[i] += cumhist[i - 1] + hist[i];
105 /* Allocate image buffer */
106 (*image_buffer) = malloc(sizeof(unsigned char) * npixels);
109 /* Linear scale (min-max) : This is the default scaling
110 * histo-eq will fail if we dont generate image_buffer here */
111 for (i = 0; i < npixels; ++i)
112 (*image_buffer)[i] = (int)(data[i]);
114 /*-----------------------------------------------------------------------*/
117 switch (scale)
118 {
119 case 1 : /* Square root */
120 scl_data = sqrt((float)JMAXVAL)/(float)JMAXVAL;
121 for (i = 0; i < npixels; ++i)
122 (*image_buffer)[i] = (int)(sqrt(data[i])/scl_data);
123 break;
125 case 2 : /* Square */
126 scl_data = pow((float)JMAXVAL,2)/(float)JMAXVAL;
127 for (i = 0; i < npixels; ++i)
128 (*image_buffer)[i] = (int)abs((pow(data[i],2) - 1.0)/scl_data);
129 break;
131 case 3 : /* Cubic */
132 scl_data = pow((float)JMAXVAL,3)/(float)JMAXVAL;
133 for (i = 0; i < npixels; ++i)
134 (*image_buffer)[i] = (int)abs((pow(data[i],3) - 1.0)/scl_data);
135 break;
137 case 4 : /* log */
138 scl_data = log(1.0 + (float)JMAXVAL)/(float)JMAXVAL;
139 for (i = 0; i < npixels; ++i)
140 (*image_buffer)[i] = (int)((log(abs(data[i]) + 1.0))/scl_data);
141 break;
143 case 5 : /* contrast stretch */
144 /* We need to go through the cumulative histogram to pick the
145 * appropriate values for datamin and datamax */
146 i = 0;
147 while (i < JMAXVAL)
148 {
149 if (cumhist[i] >= 0.01)
150 {
151 datamin = (float) i;
152 break;
153 }
154 i++;
155 }
156 i = JMAXVAL;
157 while (i > 0)
158 {
159 if (cumhist[i] <= 0.99)
160 {
161 datamax = (float) i;
162 break;
163 }
164 i--;
165 }
166 scl_data = (datamax - datamin)/(float)JMAXVAL;
167 for (i = 0; i < npixels; ++i)
168 {
169 if ((*image_buffer)[i] >= datamax)
170 (*image_buffer)[i] = JMAXVAL;
171 else if ((*image_buffer)[i] <= datamin)
172 (*image_buffer)[i] = 0;
173 else
174 (*image_buffer)[i] = (int) abs(((*image_buffer)[i]
175 - datamin)/scl_data);
176 }
177 break;
179 case 6 : /* histogram equalization */
180 for (i = 0; i < npixels; ++i)
181 (*image_buffer)[i] = cumhist[(*image_buffer)[i]] * JMAXVAL;
182 break;
183 default :
184 break;
185 }
186 }
188 /*---------------------------------------------------------------------------*
189 * RESIZE_IMAGE: Scales down/up the image_buffer using bilinear scaling
190 * Based on an article by "John" at
191 * http://tech-algorithm.com/articles/bilinear-image-scaling/
192 *---------------------------------------------------------------------------*/
193 void resize_image(long *xdim, long *ydim, float zoomfact,
194 JSAMPLE ** image_buffer)
195 {
196 int offset = 0, index = 0;
197 int A, B, C, D, x, y, gray;
198 JSAMPLE *buff;
199 unsigned int i = 0, j = 0;
200 unsigned long npixels = 0;
201 long w = *xdim, h = *ydim;
202 long zxdim = 0, zydim = 0;
203 float xdiff, ydiff, xratio, yratio;
205 zxdim = (int)(w * zoomfact);
206 zydim = (int)(h * zoomfact);
208 npixels= zxdim * zydim;
210 xratio = ((float)(w - 1))/zxdim;
211 yratio = ((float)(h - 1))/zydim;
213 /* allocate space for *buff */
214 buff = malloc(sizeof(unsigned char) * zxdim * zydim);
216 index = 0;
217 offset = 0;
218 for (i = 0; i < zydim; i++)
219 {
220 y = (int)(yratio * i);
221 ydiff = (yratio * i) - y;
223 for (j = 0; j < zxdim; j++)
224 {
225 x = (int)(xratio * j);
227 xdiff = (xratio * j) - x;
228 index = y * w + x;
230 A = (*image_buffer)[index] & 0xff;
231 B = (*image_buffer)[index + 1] & 0xff;
232 C = (*image_buffer)[index + w] & 0xff;
233 D = (*image_buffer)[index + w + 1] & 0xff;
235 gray = (int)(A * (1 - xdiff) * (1 - ydiff)
236 + B * (xdiff) * (1 - ydiff)
237 + C * (ydiff) * (1 - xdiff)
238 + D * (xdiff) * (ydiff)
239 );
240 buff[offset++] = gray;
241 }
242 }
243 *xdim = zxdim;
244 *ydim = zydim;
245 (*image_buffer) = realloc((*image_buffer), sizeof(unsigned char) * npixels);
246 for (i = 0; i < npixels; ++i)
247 (*image_buffer)[i] = buff[i];
248 free(buff);
249 }