Question

I took a Bitmap image and pulled the R, G, B ints from it for a specified row of pixels. Converted the int to a string so that I could print my 6 specific colors. I couldn’t figure out how to do it with int.

The Problem
I am able to print row 0-184 (corresponding to pixels in that row) out as a sequential data 1234… or color red, red, red, black, black, gray….

However I need to count like/same colors, display the sum of like colors, and reset a counter until that color comes up again then recount. I thought an if or if else would do it but not quite. It may be my code structure that is causing an issue?

So what I desire is:

5   red,
10  black,
2   red,
1   gray,

etc……

Here is my code, I am a beginner so criticizes on my lack of knowledge so that I may learn properly.

#include <iostream>
#include <sstream>
#include <string>
#include "EasyBMP.h"
#include "EasyBMP_BMP.h"
#include "EasyBMP_DataStructures.h"
#include "EasyBMP_VariousBMPutilities.h"

//Conversion and comparison function
void calculate(int i, int x, int p);

int main(int argc, const char * argv[])
{

BMP Image;
Image.ReadFromFile( "BMP GOES HERE 24bit" );

std::cout << "Image Height and Width: " << Image.TellHeight() << " x " << Image.TellWidth() << std::endl;

std::cout << "Enter your row: ";

int pixX = 0;
std::cin >> pixX;

//Set getpixel to top of row
int pixY  = 0;

for( pixY = 0; pixY < Image.TellHeight() ; pixY++ )
{
    std::cout << "Pixel: " << pixY + 1;

    RGBApixel Temp = Image.GetPixel(pixX,pixY);

    //Array to store pixel color ints
    int pixy[3];
    pixy[0] = Temp.Red;
    pixy[1] = Temp.Green;
    pixy[2] = Temp.Blue;

    calculate(pixy[0], pixy[1], pixy[2]);
}

return 0;
}


void calculate(int rnum, int gnum, int bnum)
{

//String which will contain the result
std::string result;

//Stream used for the conversion
std::ostringstream convert;

//Insert the textual representation of 'Number' in the characters in the stream
convert << rnum;                

convert << gnum;

convert << bnum;

// set 'Result' to the contents of the stream
result = convert.str();    

// compare result to my given value
if (result == "25500")
{
    std::cout << " RED  " << std::endl;
}
if (result == "255255255")
{
    std::cout << " WHITE " << std::endl;
}
if (result == "000")
{
    std::cout << " BLACK" << std::endl;
}
if (result == "148148148")
{
    std::cout << " GRAY " << std::endl;
}
if (result == "267326")
{
    std::cout << " GREEN " << std::endl;
}
if (result == "2551260")
{
    std::cout << " ORANGE " << std::endl;
}
}

Following is the working code. Note that if you use it that my image only has 6 specific colors. To change the print out one would have to modify the switch statement cases as desired.

#include <iostream>
#include <vector>
#include "EasyBMP.h"    
#include "EasyBMP_BMP.h"
#include "EasyBMP_DataStructures.h"
#include "EasyBMP_VariousBMPutilities.h"

long toRGB(long red, long grn, long blu);


int main(int argc, const char * argv[])
{

BMP Image;
Image.ReadFromFile( "Your BMP HERE" );

std::cout << "Image Height and Width: " << Image.TellHeight() << " x " << Image.TellWidth() << std::endl;

std::cout << "Enter your row: ";

int pixX = 0;
std::cin >> pixX;
if (pixX != 0)                              //Subtract one from input if not 0, image starts at 0,0
{
    pixX -= 1;
}

long pop  = 0;
long pop1 = 0;

RGBApixel current = Image.GetPixel(pixX,0);

long pixy1[3];                                        //Array to store pixel color ints
pixy1[0] = current.Red;
pixy1[1] = current.Green;
pixy1[2] = current.Blue;

pop1 = toRGB(pixy1[0], pixy1[1], pixy1[2]);


int count = 0;
for( int pixY = 0; pixY < Image.TellHeight() ; pixY++ )
{
    RGBApixel Temp = Image.GetPixel(pixX,pixY);

    long pixy[3];                                        //Array to store pixel color ints
    pixy[0] = Temp.Red;
    pixy[1] = Temp.Green;
    pixy[2] = Temp.Blue;

    pop = toRGB(pixy[0], pixy[1], pixy[2]);

    if (pop == pop1)
    {
        count++;
    }
    else
    {
        switch (pop1) {
            case 0:
                std::cout << "(" << count << ")\t" << "BLACK\n" << std::endl;
                break;
            case 16711680:
                std::cout << "(" << count << ")\t" << "RED\n" << std::endl;
                break;
            case 9737364:
                std::cout << "(" << count << ")\t" << "GRAY\n" << std::endl;
                break;
            case 16777215:
                std::cout << "(" << count << ")\t" << "WHITE\n" << std::endl;
                break;
            case 1722650:
                std::cout << "(" << count << ")\t" << "GREEN\n" << std::endl;
                break;
            case 16743936:
                std::cout << "(" << count << ")\t" << "ORANGE\n" << std::endl;
                break;
            default:
                std::cout << " !!!NO Specified COLOR For!!! " << pop1 << std::endl;
                break;
        }

        pop1 = pop;                                     //Reset the count and current     color
        count = 1;
    }
}
    if (count > 0)                                      //Returns last color and count
    {
        switch (pop1) {
            case 0:
                std::cout << "(" << count << ")\t" << "BLACK\n" << std::endl;
                break;
            case 16711680:
                std::cout << "(" << count << ")\t" << "RED\n" << std::endl;
                break;
            case 9737364:
                std::cout << "(" << count << ")\t" << "GRAY\n" << std::endl;
                break;
            case 16777215:
                std::cout << "(" << count << ")\t" << "WHITE\n" << std::endl;
                break;
            case 1722650:
                std::cout << "(" << count << ")\t" << "GREEN\n" << std::endl;
                break;
            case 16743936:
                std::cout << "(" << count << ")\t" << "ORANGE\n" << std::endl;
                break;
            default:
                std::cout << " !!!NO Specified COLOR For!!! " << pop1 << std::endl;
                break;
    }
}

return 0;
}

long toRGB(long a, long b, long c)                          //Function to convert R, G, B      values to unique value
{
long color = 0;
color |= (a & 255) << 16;
color |= (b & 255) << 8;
color |= (c & 255);

return color;
}

Answer 1

I didn’t really understand your question before, so I wrote a new answer more appropriate to what you’re asking.

I think you can get what you want with something like this (modifying your code):

RGBApixel current = Image.GetPixel(pixX,0);
int count = 0;
for( pixY = 0; pixY < Image.TellHeight() ; pixY++ )
{
    RGBApixel Temp = Image.GetPixel(pixX,pixY);
    if (Temp == current)
    {
         count++;
    }
    else
    {
         // same-color sequence ended
         // Add code here to print out current color and count
         --- your output code ----

         // now reset the count and current color
         current = Temp;
         count = 1;
    }
}

// Now just print out the last sequence
if (count > 0)
{
    --- your output code here again ---
}      

One thing I’m not sure is how, if at all, the == operator is defined for RGBApixel. If it isn’t defined or doesn’t seem to equate pixels based on their color, just write a function like pixelsAreEqual(RBGApixel p1, RGBApixel p2) that takes two pixels and returns true if they have the same RGB values.