X-Git-Url: https://cads.iiap.res.in/gitview/?p=fits2jpeg.git;a=blobdiff_plain;f=src%2Fimage.c;fp=src%2Fimage.c;h=d1c22f07bfa79d885c512505d8258a5dc1eff96e;hp=7a068e95892274491916e9ebca6027524081b3e6;hb=60d065b23a2bdd48da5b8ef3ce591b7b0313c979;hpb=e31da38fa70e45758bd0c82b124c018c25e78e23

diff --git a/src/image.c b/src/image.c
index 7a068e9..d1c22f0 100644
--- a/src/image.c
+++ b/src/image.c
@@ -24,7 +24,10 @@
 /*Header Definitions*/
 #include "fits2jpeg.h"
 
-void scale_image(int scale, int npixels,
+/*---------------------------------------------------------------------------*
+ * 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;
@@ -34,7 +37,7 @@ void scale_image(int scale, int npixels,
     float scl_data = 0.0;
 
 
-    /* first find min & max in data */
+    /* first find min & max in data                                          */
     datamax = -1.0 * FLT_MAX;
     datamin = FLT_MAX;
     for (i = 0; i < npixels; ++i)
@@ -43,19 +46,22 @@ void scale_image(int scale, int npixels,
         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                     */
+
+    /* 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   */
+
+    /* 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[]       */
-    /*-------------------------------------------------------------------*/
+    /* initialize image histogram. ensure all are zeroes in hist[]           */
+    /*-----------------------------------------------------------------------*/
     for (i = 0; i <= JMAXVAL; ++i) hist[i] = 0;
 
     /* construct the image histogram */
@@ -69,11 +75,11 @@ void scale_image(int scale, int npixels,
         cumhist[i] += cumhist[i - 1] + hist[i];
 
     /* Linear scale (min-max) : This is the default scaling
-     * if we dont generate image_buffer here, histo-eq will fail */
+     * 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)
@@ -140,7 +146,8 @@ void scale_image(int scale, int npixels,
                 else if (image_buffer[i] <= datamin)
                     image_buffer[i] = 0;
                 else
-                    image_buffer[i] = (int) abs((image_buffer[i] - datamin)/scl_data);
+                    image_buffer[i] = (int) abs((image_buffer[i]
+                                    - datamin)/scl_data);
             }
             break;
 
@@ -148,7 +155,7 @@ void scale_image(int scale, int npixels,
             /* histogram equalization */
             printinfo("Performing Histogram Equalization");
             for (i = 0; i <  npixels; ++i)
-                image_buffer[i] = cumhist[image_buffer[i]] * 255;
+                image_buffer[i] = cumhist[image_buffer[i]] * JMAXVAL;
             break;
         default :
             printinfo("Using linear scale");
@@ -156,3 +163,65 @@ void scale_image(int scale, int npixels,
     }
 
 }
+
+/*---------------------------------------------------------------------------*
+ * 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];
+}