Inverting bitmap image turns the image black. But inconsistently

Question

I am trying to negate a bitmap image with some code written in C.

1. When I run the code for the Lena image (let me call it LenaImage1) the first time I get a black image (LenaImage2). When I run the same code on the image I get back the original image (LenaImage1). This implies that the code works correctly right? When I view and save (as bitmap) LenaImage2 using MATLAB I don't get the black image, meaning that I can see it as the complimented image(MATLAB returns the same output).

2. And when I run the same C code on a second image (MountainImage1) I get a really bad image (MounainImage2), with lots of pseudo colouring but NOT the black image as the output. And when I run code to compliment MounainImage1 in MATLAB I get what looks like the correct image without the pseudo colouring. And when I run the C code on the MountainImage2 I get back the original image (i.e. MountainImage1).

Running the code on a third image shows behaviour similar to the Lena image. All of the images mentioned can be found here.

Another answer mentions that bitmap images don't support transparency.

Is it this transparency issue that I see here? If yes, why do I not see consistent behaviour of this transparency issue in all the images? Also, how is it that when I view and save LenaImage2 as well as MountainImage2 using MATLAB and it does not show the black image or any pseudo coloring? How can I correct my C code?

Here is the code that inverts the image:

The file header declarations in my header file:

            #pragma pack(push,1)
            typedef struct bmpFileHeader
            {
                unsigned short bfType;       /*specifies the file type*/
                unsigned long bfSize;        /*specifies the size in bytes of the bitmap file*/
                unsigned short bfReserved1;  /*reserved; must be 0*/
                unsigned short bfReserved2;  /*reserved; must be 0*/
                unsigned long bfOffBits;     /*species the offset in bytes from the bitmapfileheader to the bitmap bits*/
            }bmpFileHeader;

            typedef struct bmpInfoHeader
            {
                unsigned long biSize;           /*Size of bmpInfoHeader*/
                unsigned long biWidth;          /*specifies width in pixels*/
                unsigned long biHeight;         /*species height in pixels*/
                unsigned short biPlanes;        /*specifies the number of color planes, must be 1*/
                unsigned short biBitCount;      /*specifies the number of bit per pixel*/
                unsigned long biCompression;    /*spcifies the type of compression*/
                unsigned long biSizeImage;      /*size of image in bytes*/
                unsigned long biXPelsPerMeter;  /*number of pixels per meter in x axis*/
                unsigned long biYPelsPerMeter;  /*number of pixels per meter in y axis*/
                unsigned long biClrUsed;        /*number of colors used by the bitmap*/
                unsigned long biClrImportant;   /*number of colors that are important*/
            }bmpInfoHeader;
            #pragma pack(pop)

The code that does the work:

            void ImageData(FILE *filePtr)
            {
                bmpFileHeader FileHeader;
                bmpInfoHeader InfoHeader;
                char *bmpImageData;    /*array to hold the image data*/
                size_t imagedataSize=0,check=0;
                int y;


                /*read the bitmap file header*/
                check=fread(&FileHeader, sizeof(bmpFileHeader),1,filePtr);
                printf("checkFileHeader=%d\n",check);

                /*verify that this is a bmp file by check bitmap id*/
                if (FileHeader.bfType !=0x4D42)
                {
                    fclose(filePtr);
                    printf("ImageData:Is not a BMP file\n");
                    return;
                }

                /*read the bitmap info header*/
                check=fread(&InfoHeader, sizeof(InfoHeader),1,filePtr);
                printf("checkInfoHeader=%d\n",check);

                /*Allocate space for the image data*/

                bmpImageData=(char*)malloc(InfoHeader.biSizeImage);
                if(bmpImageData==NULL){
                    printf("Couldn't allocate memory for ImageData\n");
                    return;
                }
                /*move the file position to the point where the aligned image data begins*/
                check=fseek(filePtr,FileHeader.bfOffBits,SEEK_SET);
                if(check!=0){
                    printf("Error seeking file\n");
                    return;
                }
                /*Copy the image data to bmpImageData*/
                check=fread(bmpImageData,InfoHeader.biSizeImage,1,filePtr);
                if(check!=1){
                    printf("Error reading image data\n");
                    return
                }

                /*Moving filePtr to position where image data begins*/
                check=fseek(filePtr,FileHeader.bfOffBits,SEEK_SET);
                if(check!=0){
                    printf("Error seeking file\n");
                    return;
                }
                /*Manipulating the image data*/
                for(y=0;y<InfoHeader.biSizeImage;y++){
                    bmpImageData[y]=255-bmpImageData[y];
                }
                check=fwrite(bmpImageData,InfoHeader.biSizeImage,1,filePtr);
                if(check!=1)
                    printf("Error writing image data to file");

                free(bmpImageData);

            }

All of the images I am using are greyscale images with 8-bit pixel depth. I am using the CodeBlocks IDE (GNU GCC compiler) on a x86 machine running Windows 8.

Addition: This is what the header fields for the Lena image read:

            File Header Information
            FileHeaderSize=14
            bfType=4d42
            bfSize=263222
            bfReserved1=0
            bfReserved2=0
            bfOffBits=1078

            Info Header Information
            InfoHeaderSize=40
            biSize=40
            biHeight=512
            biWidth=512
            biPlanes=1
            biBitCount=8
            biCompression=0
            biSizeImage=262144
            biXPelsPerMeter=0
            biYPelsPerMeter=0
            biClrUsed=256
            biClrImportant=256

Answer 1

The bitcount=8, which means that a colour table (palette) is mandatory - see here. That means that the values in the pixel array (i.e. your variable bmpImageData) are not colours, but actually indexes into the palette. As such, you cannot sensibly directly modify the bmpImageData.

So, if pixel[0,0] contains, say, 3, you have to look up the 3rd entry in the colour palette to work out what colour that corresponds to.

The palette should be after the BITMAPINFOHEADER and the DIB, so it is from byte 55-435.

I suggest you print out those bytes in hex and have a look at them. I am guessing you will see that they go RGBA, RGBA, RGBA but that the A (alpha or transparency) will be zero, i.e. unused. So I would expect them to look like this, with R=G=B (since they are greyscale):

xx xx xx 00 yy yy yy 00 zz zz zz 00

Then, in order to invert your image, change each xx to 255-xx (and likewise y and z) there in the palette without needing to process all the bmpImageData at all.

There are some inconsistencies in my answer, but that is because I can only see a JPEG file when I am trying to debug a BMP file. One inconsistency is that the space between the DIB and the pixel array is 436-54 bytes, i.e. 382 bytes which is not divisible by 3 or 4 and therefore doesn't make for a very sensible palette size using either 3 or 4 bytes per entry... but grab the hex data and we will take a look and see if we can get closer to a correct answer.

If you use ImageMagick (available for free for Unix/Linux and Windows from here), you can use the identify command as follows to help you debug your code:

  identify -verbose lena.bmp

  Format: BMP (Microsoft Windows bitmap image)
  Class: PseudoClass
  Geometry: 512x512+0+0
  Units: PixelsPerCentimeter
  Type: Grayscale
  Base type: Grayscale
  Endianess: Undefined
  Colorspace: Gray
  Depth: 8-bit
  Channel depth:
    gray: 8-bit
  Channel statistics:
    Pixels: 262144
    Gray:
      min: 28 (0.109804)
      max: 244 (0.956863)
      mean: 124.071 (0.486554)
      standard deviation: 47.9288 (0.187956)
      kurtosis: -0.839484
      skewness: -0.0822738
  Colors: 28
  Histogram:
       474: ( 28, 28, 28) #1C1C1C gray(28)
      4477: ( 36, 36, 36) #242424 gray(36)
     13395: ( 44, 44, 44) #2C2C2C gray(44)
     15131: ( 52, 52, 52) #343434 gray(52)
      9461: ( 60, 60, 60) #3C3C3C gray(60)
      6569: ( 68, 68, 68) #444444 gray(68)
      7027: ( 76, 76, 76) #4C4C4C gray(76)
      7733: ( 84, 84, 84) #545454 gray(84)
     10330: ( 92, 92, 92) #5C5C5C gray(92)
     14865: (100,100,100) #646464 gray(100)
     12095: (108,108,108) #6C6C6C gray(108)
     11631: (116,116,116) #747474 gray(116)
     16153: (124,124,124) #7C7C7C gray(124)
     17429: (132,132,132) #848484 gray(132)
     17623: (140,140,140) #8C8C8C gray(140)
     18636: (148,148,148) #949494 gray(148)
     19688: (156,156,156) #9C9C9C gray(156)
     12554: (164,164,164) #A4A4A4 gray(164)
      9848: (172,172,172) #ACACAC gray(172)
      7380: (180,180,180) #B4B4B4 gray(180)
      5589: (188,188,188) #BCBCBC gray(188)
      7162: (196,196,196) #C4C4C4 gray(196)
      7451: (204,204,204) #CCCCCC gray(204)
      6699: (212,212,212) #D4D4D4 gray(212)
      2293: (220,220,220) #DCDCDC gray(220)
       425: (228,228,228) #E4E4E4 gray(228)
        22: (236,236,236) #ECECEC gray(236)
         4: (244,244,244) #F4F4F4 gray(244)
  Colormap entries: 256
  Colormap:
         0: (  0,  0,  0) #000000 gray(0)
         1: (128,  0,  0) #800000 gray(128)
         2: (  0,128,  0) #008000 gray(0)
         3: (128,128,  0) #808000 gray(128)
         4: (  0,  0,128) #000080 gray(0)
         5: (128,  0,128) #800080 gray(128)
         6: (  0,128,128) #008080 gray(0)
         7: (128,128,128) #808080 gray(128)
         8: ( 28, 28, 28) #1C1C1C gray(28)
         9: (140,140,140) #8C8C8C gray(140)
        10: ( 84, 84, 84) #545454 gray(84)
        11: (196,196,196) #C4C4C4 gray(196)
        12: ( 60, 60, 60) #3C3C3C gray(60)
        13: (172,172,172) #ACACAC gray(172)
        14: (116,116,116) #747474 gray(116)
        15: (228,228,228) #E4E4E4 gray(228)
        16: ( 44, 44, 44) #2C2C2C gray(44)
        17: (156,156,156) #9C9C9C gray(156)
        18: (100,100,100) #646464 gray(100)
        19: (212,212,212) #D4D4D4 gray(212)
        20: ( 76, 76, 76) #4C4C4C gray(76)
        21: (188,188,188) #BCBCBC gray(188)
        22: (132,132,132) #848484 gray(132)
        23: (244,244,244) #F4F4F4 gray(244)
        24: ( 36, 36, 36) #242424 gray(36)
        25: (148,148,148) #949494 gray(148)
        26: ( 92, 92, 92) #5C5C5C gray(92)
        27: (204,204,204) #CCCCCC gray(204)
        28: ( 68, 68, 68) #444444 gray(68)
        29: (180,180,180) #B4B4B4 gray(180)
        30: (124,124,124) #7C7C7C gray(124)
        31: (236,236,236) #ECECEC gray(236)
        32: ( 52, 52, 52) #343434 gray(52)
        33: (164,164,164) #A4A4A4 gray(164)
        34: (108,108,108) #6C6C6C gray(108)
        35: (220,220,220) #DCDCDC gray(220)
        36: (  0,  0,  0) #000000 gray(0)
        37: (  0,  0,  0) #000000 gray(0)
        38: (  0,  0,  0) #000000 gray(0)
        39: (  0,  0,  0) #000000 gray(0)
        40: (  0,  0,  0) #000000 gray(0)
        41: (  0,  0,  0) #000000 gray(0)
        42: (  0,  0,  0) #000000 gray(0)
        43: (  0,  0,  0) #000000 gray(0)
        44: (  0,  0,  0) #000000 gray(0)
        45: (  0,  0,  0) #000000 gray(0)
        46: (  0,  0,  0) #000000 gray(0)
        47: (  0,  0,  0) #000000 gray(0)
        48: (  0,  0,  0) #000000 gray(0)
        49: (  0,  0,  0) #000000 gray(0)
        50: (  0,  0,  0) #000000 gray(0)
        51: (  0,  0,  0) #000000 gray(0)
        52: (  0,  0,  0) #000000 gray(0)
        53: (  0,  0,  0) #000000 gray(0)
        54: (  0,  0,  0) #000000 gray(0)
        55: (  0,  0,  0) #000000 gray(0)
        56: (  0,  0,  0) #000000 gray(0)
        57: (  0,  0,  0) #000000 gray(0)
        58: (  0,  0,  0) #000000 gray(0)
        59: (  0,  0,  0) #000000 gray(0)
        60: (  0,  0,  0) #000000 gray(0)
        61: (  0,  0,  0) #000000 gray(0)
        62: (  0,  0,  0) #000000 gray(0)
        63: (  0,  0,  0) #000000 gray(0)
        64: (  0,  0,  0) #000000 gray(0)
        65: (  0,  0,  0) #000000 gray(0)
        66: (  0,  0,  0) #000000 gray(0)
        67: (  0,  0,  0) #000000 gray(0)
        68: (  0,  0,  0) #000000 gray(0)
        69: (  0,  0,  0) #000000 gray(0)
        70: (  0,  0,  0) #000000 gray(0)
        71: (  0,  0,  0) #000000 gray(0)
        72: (  0,  0,  0) #000000 gray(0)
        73: (  0,  0,  0) #000000 gray(0)
        74: (  0,  0,  0) #000000 gray(0)
        75: (  0,  0,  0) #000000 gray(0)
        76: (  0,  0,  0) #000000 gray(0)
        77: (  0,  0,  0) #000000 gray(0)
        78: (  0,  0,  0) #000000 gray(0)
        79: (  0,  0,  0) #000000 gray(0)
        80: (  0,  0,  0) #000000 gray(0)
        81: (  0,  0,  0) #000000 gray(0)
        82: (  0,  0,  0) #000000 gray(0)
        83: (  0,  0,  0) #000000 gray(0)
        84: (  0,  0,  0) #000000 gray(0)
        85: (  0,  0,  0) #000000 gray(0)
        86: (  0,  0,  0) #000000 gray(0)
        87: (  0,  0,  0) #000000 gray(0)
        88: (  0,  0,  0) #000000 gray(0)
        89: (  0,  0,  0) #000000 gray(0)
        90: (  0,  0,  0) #000000 gray(0)
        91: (  0,  0,  0) #000000 gray(0)
        92: (  0,  0,  0) #000000 gray(0)
        93: (  0,  0,  0) #000000 gray(0)
        94: (  0,  0,  0) #000000 gray(0)
        95: (  0,  0,  0) #000000 gray(0)
        96: (  0,  0,  0) #000000 gray(0)
        97: (  0,  0,  0) #000000 gray(0)
        98: (  0,  0,  0) #000000 gray(0)
        99: (  0,  0,  0) #000000 gray(0)
       100: (  0,  0,  0) #000000 gray(0)
       101: (  0,  0,  0) #000000 gray(0)
       102: (  0,  0,  0) #000000 gray(0)
       103: (  0,  0,  0) #000000 gray(0)
       104: (  0,  0,  0) #000000 gray(0)
       105: (  0,  0,  0) #000000 gray(0)
       106: (  0,  0,  0) #000000 gray(0)
       107: (  0,  0,  0) #000000 gray(0)
       108: (  0,  0,  0) #000000 gray(0)
       109: (  0,  0,  0) #000000 gray(0)
       110: (  0,  0,  0) #000000 gray(0)
       111: (  0,  0,  0) #000000 gray(0)
       112: (  0,  0,  0) #000000 gray(0)
       113: (  0,  0,  0) #000000 gray(0)
       114: (  0,  0,  0) #000000 gray(0)
       115: (  0,  0,  0) #000000 gray(0)
       116: (  0,  0,  0) #000000 gray(0)
       117: (  0,  0,  0) #000000 gray(0)
       118: (  0,  0,  0) #000000 gray(0)
       119: (  0,  0,  0) #000000 gray(0)
       120: (  0,  0,  0) #000000 gray(0)
       121: (  0,  0,  0) #000000 gray(0)
       122: (  0,  0,  0) #000000 gray(0)
       123: (  0,  0,  0) #000000 gray(0)
       124: (  0,  0,  0) #000000 gray(0)
       125: (  0,  0,  0) #000000 gray(0)
       126: (  0,  0,  0) #000000 gray(0)
       127: (  0,  0,  0) #000000 gray(0)
       128: (  0,  0,  0) #000000 gray(0)
       129: (  0,  0,  0) #000000 gray(0)
       130: (  0,  0,  0) #000000 gray(0)
       131: (  0,  0,  0) #000000 gray(0)
       132: (  0,  0,  0) #000000 gray(0)
       133: (  0,  0,  0) #000000 gray(0)
       134: (  0,  0,  0) #000000 gray(0)
       135: (  0,  0,  0) #000000 gray(0)
       136: (  0,  0,  0) #000000 gray(0)
       137: (  0,  0,  0) #000000 gray(0)
       138: (  0,  0,  0) #000000 gray(0)
       139: (  0,  0,  0) #000000 gray(0)
       140: (  0,  0,  0) #000000 gray(0)
       141: (  0,  0,  0) #000000 gray(0)
       142: (  0,  0,  0) #000000 gray(0)
       143: (  0,  0,  0) #000000 gray(0)
       144: (  0,  0,  0) #000000 gray(0)
       145: (  0,  0,  0) #000000 gray(0)
       146: (  0,  0,  0) #000000 gray(0)
       147: (  0,  0,  0) #000000 gray(0)
       148: (  0,  0,  0) #000000 gray(0)
       149: (  0,  0,  0) #000000 gray(0)
       150: (  0,  0,  0) #000000 gray(0)
       151: (  0,  0,  0) #000000 gray(0)
       152: (  0,  0,  0) #000000 gray(0)
       153: (  0,  0,  0) #000000 gray(0)
       154: (  0,  0,  0) #000000 gray(0)
       155: (  0,  0,  0) #000000 gray(0)
       156: (  0,  0,  0) #000000 gray(0)
       157: (  0,  0,  0) #000000 gray(0)
       158: (  0,  0,  0) #000000 gray(0)
       159: (  0,  0,  0) #000000 gray(0)
       160: (  0,  0,  0) #000000 gray(0)
       161: (  0,  0,  0) #000000 gray(0)
       162: (  0,  0,  0) #000000 gray(0)
       163: (  0,  0,  0) #000000 gray(0)
       164: (  0,  0,  0) #000000 gray(0)
       165: (  0,  0,  0) #000000 gray(0)
       166: (  0,  0,  0) #000000 gray(0)
       167: (  0,  0,  0) #000000 gray(0)
       168: (  0,  0,  0) #000000 gray(0)
       169: (  0,  0,  0) #000000 gray(0)
       170: (  0,  0,  0) #000000 gray(0)
       171: (  0,  0,  0) #000000 gray(0)
       172: (  0,  0,  0) #000000 gray(0)
       173: (  0,  0,  0) #000000 gray(0)
       174: (  0,  0,  0) #000000 gray(0)
       175: (  0,  0,  0) #000000 gray(0)
       176: (  0,  0,  0) #000000 gray(0)
       177: (  0,  0,  0) #000000 gray(0)
       178: (  0,  0,  0) #000000 gray(0)
       179: (  0,  0,  0) #000000 gray(0)
       180: (  0,  0,  0) #000000 gray(0)
       181: (  0,  0,  0) #000000 gray(0)
       182: (  0,  0,  0) #000000 gray(0)
       183: (  0,  0,  0) #000000 gray(0)
       184: (  0,  0,  0) #000000 gray(0)
       185: (  0,  0,  0) #000000 gray(0)
       186: (  0,  0,  0) #000000 gray(0)
       187: (  0,  0,  0) #000000 gray(0)
       188: (  0,  0,  0) #000000 gray(0)
       189: (  0,  0,  0) #000000 gray(0)
       190: (  0,  0,  0) #000000 gray(0)
       191: (  0,  0,  0) #000000 gray(0)
       192: (  0,  0,  0) #000000 gray(0)
       193: (  0,  0,  0) #000000 gray(0)
       194: (  0,  0,  0) #000000 gray(0)
       195: (  0,  0,  0) #000000 gray(0)
       196: (  0,  0,  0) #000000 gray(0)
       197: (  0,  0,  0) #000000 gray(0)
       198: (  0,  0,  0) #000000 gray(0)
       199: (  0,  0,  0) #000000 gray(0)
       200: (  0,  0,  0) #000000 gray(0)
       201: (  0,  0,  0) #000000 gray(0)
       202: (  0,  0,  0) #000000 gray(0)
       203: (  0,  0,  0) #000000 gray(0)
       204: (  0,  0,  0) #000000 gray(0)
       205: (  0,  0,  0) #000000 gray(0)
       206: (  0,  0,  0) #000000 gray(0)
       207: (  0,  0,  0) #000000 gray(0)
       208: (  0,  0,  0) #000000 gray(0)
       209: (  0,  0,  0) #000000 gray(0)
       210: (  0,  0,  0) #000000 gray(0)
       211: (  0,  0,  0) #000000 gray(0)
       212: (  0,  0,  0) #000000 gray(0)
       213: (  0,  0,  0) #000000 gray(0)
       214: (  0,  0,  0) #000000 gray(0)
       215: (  0,  0,  0) #000000 gray(0)
       216: (  0,  0,  0) #000000 gray(0)
       217: (  0,  0,  0) #000000 gray(0)
       218: (  0,  0,  0) #000000 gray(0)
       219: (  0,  0,  0) #000000 gray(0)
       220: (  0,  0,  0) #000000 gray(0)
       221: (  0,  0,  0) #000000 gray(0)
       222: (  0,  0,  0) #000000 gray(0)
       223: (  0,  0,  0) #000000 gray(0)
       224: (  0,  0,  0) #000000 gray(0)
       225: (  0,  0,  0) #000000 gray(0)
       226: (  0,  0,  0) #000000 gray(0)
       227: (  0,  0,  0) #000000 gray(0)
       228: (  0,  0,  0) #000000 gray(0)
       229: (  0,  0,  0) #000000 gray(0)
       230: (  0,  0,  0) #000000 gray(0)
       231: (  0,  0,  0) #000000 gray(0)
       232: (  0,  0,  0) #000000 gray(0)
       233: (  0,  0,  0) #000000 gray(0)
       234: (  0,  0,  0) #000000 gray(0)
       235: (  0,  0,  0) #000000 gray(0)
       236: (  0,  0,  0) #000000 gray(0)
       237: (  0,  0,  0) #000000 gray(0)
       238: (  0,  0,  0) #000000 gray(0)
       239: (  0,  0,  0) #000000 gray(0)
       240: (  0,  0,  0) #000000 gray(0)
       241: (  0,  0,  0) #000000 gray(0)
       242: (  0,  0,  0) #000000 gray(0)
       243: (  0,  0,  0) #000000 gray(0)
       244: (  0,  0,  0) #000000 gray(0)
       245: (  0,  0,  0) #000000 gray(0)
       246: (  0,  0,  0) #000000 gray(0)
       247: (  0,  0,  0) #000000 gray(0)
       248: (192,192,192) #C0C0C0 gray(192)
       249: (255,  0,  0) #FF0000 gray(255)
       250: (  0,255,  0) #00FF00 gray(0)
       251: (255,255,  0) #FFFF00 gray(255)
       252: (  0,  0,255) #0000FF gray(0)
       253: (255,  0,255) #FF00FF gray(255)
       254: (  0,255,255) #00FFFF gray(0)
       255: (255,255,255) #FFFFFF gray(255)
  Rendering intent: Perceptual
  Gamma: 0.454545
  Chromaticity:
    red primary: (0.64,0.33)
    green primary: (0.3,0.6)
    blue primary: (0.15,0.06)
    white point: (0.3127,0.329)
  Background color: gray(255)
  Border color: gray(223)
  Matte color: gray(189)
  Transparent color: gray(0)
  Interlace: None
  Intensity: Undefined
  Compose: Over
  Page geometry: 512x512+0+0
  Dispose: Undefined
  Iterations: 0
  Compression: Undefined
  Orientation: Undefined
  Properties:
    date:create: 2014-10-01T09:18:15+01:00
    date:modify: 2002-11-25T01:33:53+00:00
    signature: dcd0e6587dcdeaaba5999a9bb384473f1af19f7a4c09ffee95356ea51bec22ce
  Artifacts:
    filename: /Users/mark/Desktop/lena.bmp
    verbose: true
  Tainted: True
  Filesize: 263KB
  Number pixels: 262K
  Pixels per second: 26.21MB
  User time: 0.000u
  Elapsed time: 0:01.009
  Version: ImageMagick 6.8.9-7 Q16 x86_64 2014-09-10 http://www.imagemagick.org

As you can see there are only 28 unique colours in the image, and the palette is only partially populated, as you have noted.

Another technique that will help you debug your code is to have ImageMagick dump your entire image as text, like this - I only show the first 8 pixels, but you get the idea:

convert lena.bmp -colorspace rgb txt:- | more

# ImageMagick pixel enumeration: 512,512,255,rgb
0,0: (85,85,85)  #555555  rgb(85,85,85)
1,0: (95,95,95)  #5F5F5F  rgb(95,95,95)
2,0: (85,85,85)  #555555  rgb(85,85,85)
3,0: (95,95,95)  #5F5F5F  rgb(95,95,95)
4,0: (95,95,95)  #5F5F5F  rgb(95,95,95)
5,0: (85,85,85)  #555555  rgb(85,85,85)
6,0: (95,95,95)  #5F5F5F  rgb(95,95,95)
7,0: (85,85,85)  #555555  rgb(85,85,85)