130 lines
3.9 KiB
C
130 lines
3.9 KiB
C
#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include "imageInput.h"
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#define BUFFER_SIZE 100
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#define FILE_HEADER_STRING "__info2_image_file_format__"
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/*
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* Diese Hilfsfunktionen kümmern sich um:
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* - Das Öffnen der Datei und Überprüfen des Dateinamens
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* - Das Überprüfen des Headers, um sicherzustellen, dass es sich um die richtige Datei handelt
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* - Das Einlesen der Metadaten (Anzahl der Bilder, Bildbreite und -höhe)
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* -> Die Hilfsfunktionen garantieren, dass die Datei gültig ist, bevor mit dem Einlesen der Bilddaten fortgefahren wird.
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*/
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static FILE *openImageFile(const char *path) // Checks if the given filename pointer is valid (not NULL).
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{
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if (path == NULL)
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{
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return NULL;
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}
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return fopen(path, "rb"); // opening document in binary mode
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}
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static int readAndCheckHeader(FILE *file) // gets the length of the header text
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{
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size_t headerLength = strlen(FILE_HEADER_STRING);
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char buffer[BUFFER_SIZE];
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if (headerLength + 1 > BUFFER_SIZE) // checks if buffer is big enough for header size
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{
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return 0;
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}
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if (fread(buffer, 1, headerLength, file) != headerLength) // Checks if reading the expected number of header bytes from the file succeeded
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{
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return 0;
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}
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buffer[headerLength] = '\0'; // add string terminator so the header becomes a valid C-string
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if (strcmp(buffer, FILE_HEADER_STRING) != 0) // checks if the expected header matches the header read from the file
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{
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return 0;
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}
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return 1; /* Header ok */
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}
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static int readImageMetaData(FILE *file, // reads the metadata (count, width, height) from the file and stores them in the provided pointers
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unsigned short *count,
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unsigned short *width,
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unsigned short *height)
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{
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if (fread(count, sizeof(unsigned short), 1, file) != 1) // read the number of images from the file
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{
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return 0;
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}
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if (fread(width, sizeof(unsigned short), 1, file) != 1) // reads the image width
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{
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return 0;
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}
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if (fread(height, sizeof(unsigned short), 1, file) != 1) // reads the image height
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{
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return 0;
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}
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if (*count == 0 || *width == 0 || *height == 0) // check for invalid metadata (count, width or height cannot be zero)
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{
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return 0;
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}
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return 1;
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}
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GrayScaleImageSeries *readImages(const char *path)
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{
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// 1. Open the file
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FILE *file = openImageFile(path);
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if (file == NULL) {
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return NULL;
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}
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// 2. Check the header
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if (!readAndCheckHeader(file)) {
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return NULL;
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}
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// 3. Read image metadata
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unsigned short count, width, height;
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if (!readImageMetaData(file, &count, &width, &height)) {
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return NULL;
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}
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// 4. Allocate memory for image series
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GrayScaleImageSeries *series = malloc(sizeof(GrayScaleImageSeries)); // Allocate memory for the image series, images, and labels. Return NULL if allocation fails.
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if (series == NULL) {
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return NULL;
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}
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series->count = count;
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series->images = calloc(count, sizeof(GrayScaleImage));
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series->labels = malloc(count * sizeof(unsigned char));
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if (series->images == NULL || series->labels == NULL) {
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free(series);
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return NULL;
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}
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// 5. Read the images and labels
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for (unsigned int i = 0; i < count; i++)
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{
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GrayScaleImage *image = &series->images[i];
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unsigned char *label = &series->labels[i];
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if (fread(image->buffer, sizeof(GrayScalePixelType), width * height, file) != width * height) // Check if the correct number of pixel values (width * height) were read for the image
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{
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return 0;
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}
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if (fread(label, sizeof(unsigned char), 1, file) != 1) // Check if the label for the image was successfully read (1 byte)
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{
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return 0;
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}
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}
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return series;
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}
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