diff --git a/src/image.c b/src/image.c
--- a/src/image.c
+++ b/src/image.c
#include "fits2jpeg.h"
/*---------------------------------------------------------------------------*
+ * READ_FITS: To reads data from a fits image file.. (isn't that obvious?)
+ *---------------------------------------------------------------------------*/
+void read_fits(char * fits_file_name, long * xdim, long * ydim, float ** data)
+{
+ fitsfile *fptr;
+ int status = 0, nfound, anynull;
+ long naxes[2];
+ long npixels;
+ float nullval = 0.0;
+
+ fits_open_file(&fptr, fits_file_name, READONLY, &status);
+ fits_read_keys_lng(fptr, "NAXIS", 1, 2, naxes, &nfound, &status);
+ if (status)
+ printerro(strcat(fits_file_name, " <-- Failed to open the file"));
+
+ /* Read in data */
+ npixels = naxes[0] * naxes[1];
+ (*data) = malloc(sizeof(float) * npixels);
+
+ nullval = 0;
+ if (fits_read_img(fptr, TFLOAT, 1, npixels, &nullval, (*data), &anynull,
+ &status))
+ printerro(strcat(fits_file_name, " has no valid fits image data"));
+
+ *xdim = naxes[0];
+ *ydim = naxes[1];
+
+ fits_close_file(fptr, &status);
+}
+
+/*---------------------------------------------------------------------------*
* SCALE_PIXELS: Changes the pixel scale to linear/log/sqroot/etc..
*---------------------------------------------------------------------------*/
-void scale_pixels(int scale, unsigned int npixels,
- float *data, JSAMPLE *image_buffer)
+void scale_pixels(int scale, unsigned int npixels, float *data,
+ JSAMPLE ** image_buffer)
{
unsigned int i = 0;
int JMAXVAL = 255;
/* the dynamic range is reduced to 255 for jpeg */
scl_data = (datamax - datamin)/(float)JMAXVAL;
+ /* we will end up with segfaults if scl_data = 0 */
+ if (scl_data == 0) scl_data = 1;
+
for (i = 0; i < npixels; ++i)
data[i] = (data[i] - datamin)/scl_data;
for (i = 1; i <= JMAXVAL; ++i)
cumhist[i] += cumhist[i - 1] + hist[i];
+ /* Allocate image buffer */
+ (*image_buffer) = malloc(sizeof(unsigned char) * npixels);
+
+
/* 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]);
+ (*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);
+ (*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);
+ (*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);
+ (*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);
+ (*image_buffer)[i] = (int)((log(abs(data[i]) + 1.0))/scl_data);
break;
- case 5 :
- /* contrast stretch */
- printinfo("Performing histogram stretch (normalization)");
-
+ case 5 : /* contrast stretch */
/* We need to go through the cumulative histogram to pick the
- * appropriate values for datamin and datamax */
+ * appropriate values for datamin and datamax */
i = 0;
while (i < JMAXVAL)
{
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;
+ 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]
+ (*image_buffer)[i] = (int) abs(((*image_buffer)[i]
- datamin)/scl_data);
}
break;
- case 6 :
- /* histogram equalization */
- printinfo("Performing Histogram Equalization");
+ case 6 : /* histogram equalization */
for (i = 0; i < npixels; ++i)
- image_buffer[i] = cumhist[image_buffer[i]] * JMAXVAL;
+ (*image_buffer)[i] = cumhist[(*image_buffer)[i]] * JMAXVAL;
break;
default :
- printinfo("Using linear scale");
break;
}
-
}
/*---------------------------------------------------------------------------*
- * RESIZE_IMAGE: Scales down/up the image_buffer
+ * RESIZE_IMAGE: Scales down/up the image_buffer using bilinear scaling
+ * Based on an article by "John" at
+ * http://tech-algorithm.com/articles/bilinear-image-scaling/
*---------------------------------------------------------------------------*/
-void resize_image(long *xdim, long *ydim, float zoomfact, JSAMPLE *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;
@@ -186,8 +216,8 @@ void resize_image(long *xdim, long *ydim, float zoomfact, JSAMPLE *image_buffer)
xratio = ((float)(w - 1))/zxdim;
yratio = ((float)(h - 1))/zydim;
- /* allocate space for *buff */
- buff = (unsigned char *) malloc(sizeof(char) * zxdim * zydim);
+ /* allocate space for *buff */
+ buff = malloc(sizeof(unsigned char) * zxdim * zydim);
index = 0;
offset = 0;
@@ -203,10 +233,10 @@ void resize_image(long *xdim, long *ydim, float zoomfact, JSAMPLE *image_buffer)
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;
+ 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)
@@ -218,10 +248,8 @@ void resize_image(long *xdim, long *ydim, float zoomfact, JSAMPLE *image_buffer)
}
*xdim = zxdim;
*ydim = zydim;
- image_buffer = realloc(image_buffer, sizeof(char) * npixels);
- if (!image_buffer)
- printerro("Failed to allocate memory");
-
+ (*image_buffer) = realloc((*image_buffer), sizeof(unsigned char) * npixels);
for (i = 0; i < npixels; ++i)
- image_buffer[i] = buff[i];
+ (*image_buffer)[i] = buff[i];
+ free(buff);
}