From 82c7c1b9ee5603a041e9b0c9a7b18877f672f6fa Mon Sep 17 00:00:00 2001
From: Brandon Rodriguez <brodriguez8774@gmail.com>
Date: Fri, 23 Apr 2021 19:28:52 -0400
Subject: [PATCH] Correct handling of greyscale (P5) bitmap images as input
---
documents/references.md | 19 ++++++--------
part_1/image.cu | 58 +++++++++++++++++++++++++++++------------
2 files changed, 50 insertions(+), 27 deletions(-)
diff --git a/documents/references.md b/documents/references.md
index 9af7096..0962eb9 100644
--- a/documents/references.md
+++ b/documents/references.md
@@ -56,6 +56,9 @@ Various references used in project.
* Setting Double Precision - <https://stackoverflow.com/a/16280182>
* Saving Precision without Immediate Output to Console - <https://stackoverflow.com/a/48945767>
+#### Error - Files Compiling without "Standard" C++ Library Access
+<https://stackoverflow.com/a/10271117>
+
## CUDA References
@@ -69,15 +72,9 @@ Various references used in project.
<https://cuda-tutorial.readthedocs.io/en/latest/tutorials/tutorial01/>
-## General Errors
-
-#### Files Compiling without "Standard" C++ Library Access
-<https://stackoverflow.com/a/10271117>
-
-
-
-
-
-# c++ manipulate pixels in image
+## Other
+### Manipulating Image Pixels
+<https://www.scratchapixel.com/lessons/digital-imaging/simple-image-manipulations>
-https://www.scratchapixel.com/lessons/digital-imaging/simple-image-manipulations
+### Portable Bitmap Formats
+<https://en.wikipedia.org/wiki/Netpbm>
diff --git a/part_1/image.cu b/part_1/image.cu
index ee9c2b1..15dd08a 100644
--- a/part_1/image.cu
+++ b/part_1/image.cu
@@ -91,15 +91,25 @@ void Image::import_image_file() {
logger.error("Failed to open file \"" + input_path + "\"");
} else {
// File opened. Grab data.
- std::string header;
- input_file >> header;
- // if (strcmp(header.c_str(), "P6") != 0) {
- // // throw("Can't read input file");
- // logger.error("Wrong file type, oops: ");
- // logger.error(header);
- // logger.error(input_path);
- // logger.error("");
- // }
+ std::string header_format;
+ input_file >> header_format;
+
+ // Check image data format type.
+ if (strcmp(header_format.c_str(), "P6") == 0) {
+ // P6 indicates standard "binary RGB format".
+ logger.debug("Image is binary RGB format.");
+
+ } else if (strcmp(header_format.c_str(), "P5") == 0) {
+ // P5 indicates standard "binary greyscale format".
+ logger.debug("Image is binary greyscale format.");
+
+ } else {
+ // throw("Can't read input file");
+ logger.error("");
+ logger.error("Image: \"" + input_path + "\"");
+ logger.error("Unhandled image format type: " + header_format);
+ return;
+ }
// Save image values to class.
input_file >> width >> height >> bit_depth;
@@ -110,13 +120,29 @@ void Image::import_image_file() {
// Skip empty lines in necessary until we get to the binary data.
input_file.ignore(256, '\n');
- // Read each pixel one by one and convert bytes to floats.
- unsigned char pix[3];
- for (int index = 0; index < width * height; ++index) {
- input_file.read(reinterpret_cast<char *>(pix), 3);
- pixel_arr[index].r = pix[0] / 255.f;
- pixel_arr[index].g = pix[1] / 255.f;
- pixel_arr[index].b = pix[2] / 255.f;
+ // Read pixels based on image format.
+ if (strcmp(header_format.c_str(), "P6") == 0) {
+ // Binary RBG format.
+ // Read each pixel one by one and convert RGB channel bytes to floats.
+ unsigned char pixel[3];
+ for (int index = 0; index < width * height; ++index) {
+ input_file.read(reinterpret_cast<char *>(pixel), 3);
+ pixel_arr[index].r = pixel[0] / 255.f;
+ pixel_arr[index].g = pixel[1] / 255.f;
+ pixel_arr[index].b = pixel[2] / 255.f;
+ }
+ } else if (strcmp(header_format.c_str(), "P5") == 0) {
+ // Binary RBG format.
+ // Read each pixel one by one and convert bytes to floats.
+ unsigned char* pixel;
+ pixel = (unsigned char*)calloc(1, sizeof(unsigned char));
+ for (int index = 0; index < width * height; ++index) {
+ input_file.read(reinterpret_cast<char *>(pixel), 1);
+ pixel_arr[index].r = *pixel / 255.f;
+ pixel_arr[index].g = *pixel / 255.f;
+ pixel_arr[index].b = *pixel / 255.f;
+ }
+ free(pixel);
}
}
--
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