Problème après la compression d'image c sharp

Version imprimable

Bonjour, je cherche à modifier les pixels de mon image compressé.alors je me suis servis de la méthode Lookbit.
j'ai trouvé un problème au niveau de la modification des pixels de l'image compressé.
voici mon code
pour le codeur Jpeg

Code:

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private ImageCodecInfo GetEncoderInfo(String mimeType)
        {
            try
            {
                int j;
                ImageCodecInfo[] encoders;
                encoders = ImageCodecInfo.GetImageEncoders();
                for (j = 0; j < encoders.Length; ++j)
                {
                    if (encoders[j].MimeType == mimeType)
                        return encoders[j];
                }
                return null;
            }
            catch (Exception) { return null; }
        }
 
        private ImageCodecInfo GetEncoder(ImageFormat format)
      {
 
    ImageCodecInfo[] codecs = ImageCodecInfo.GetImageDecoders();
 
    foreach (ImageCodecInfo codec in codecs)
    {
        if (codec.FormatID == format.Guid)
        {
            return codec;
        }
    }
    return null;
}

Pour le compresseur

Code:

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private void ApplyChanges(int taux)
        {
 
 
 
 
            ImageCodecInfo jpgEncoder = GetEncoder(ImageFormat.Jpeg);
 
    // Create an Encoder object based on the GUID
    // for the Quality parameter category.
    System.Drawing.Imaging.Encoder myEncoder =
        System.Drawing.Imaging.Encoder.Quality;
 
    // Create an EncoderParameters object.
    // An EncoderParameters object has an array of EncoderParameter
    // objects. In this case, there is only one
    // EncoderParameter object in the array.
 
 
            try
            { EncoderParameters myEncoderParameters = new EncoderParameters(1);
 
            EncoderParameter myEncoderParameter = new EncoderParameter(myEncoder,(long)taux);
            myEncoderParameters.Param[0] = myEncoderParameter;
           Rectangle rect = new Rectangle(0, 0, bmp.Width, bmp.Height);
            System.Drawing.Imaging.BitmapData bmpData =
             bmp.LockBits(rect, System.Drawing.Imaging.ImageLockMode.ReadWrite,
              bmp.PixelFormat);
 
            // Get the address of the first line.
            IntPtr ptr = bmpData.Scan0;
 
            // Declare an array to hold the bytes of the bitmap.
            // This code is specific to a bitmap with 24 bits per pixels.
            int bytes = bmp.Width * bmp.Height * 3;
            byte[] rgbValues = new byte[bytes];
 
            // Copy the RGB values into the array.
            System.Runtime.InteropServices.Marshal.Copy(ptr, rgbValues, 0, bytes);
 
            // Set every red value to 255.  
            for (int counter = 0; counter < rgbValues.Length - 2; counter += 3)
            {
 
                rgbValues[counter] = (byte)(rgbValues[counter] +255);
                rgbValues[counter + 1] = (byte)(rgbValues[counter + 1] + 255);
                rgbValues[counter + 2] = (byte)(rgbValues[counter + 2] + 255);
 
            }
            // Copy the RGB values back to the bitmap
            System.Runtime.InteropServices.Marshal.Copy(rgbValues, 0, ptr, bytes);
 
            liveBitmap = new MemoryStream();
 
            bmp.Save(liveBitmap, jpgEncoder, myEncoderParameters);
 
 
            }
 
            catch (Exception e)
            {
                MessageBox.Show(e.ToString());
            }
        }

Merci:P

24/03/2016, 22h30
Michel_75

a l'aide les amis orientez moi :aie:

bonjour
Ton code est pipe car il est confus ( separation des taches suivant leur fonctions) ,comporte des omissions ,et des presomptions sur le PixelFormat (revoir l'API IMAGING en profondeur et les differents PixelFormats des images avant de les manipuler)....

code revu avec un form d'exemple :

Code:

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using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Windows.Forms;
using System.Drawing.Imaging;
using System.IO;
using System.Runtime.InteropServices;
 
namespace WinLockBit
{
    public partial class Form1 : Form
    {
        //rappel : un Octet (Byte anglais)  contient 8 bits....
 
        private int bitPerPixel; // haut parleur : nbre de Bits par pixel !!!
        private int nbBytes;     // haut parleur : nbre d' Octets par pixel !!!
 
        private Bitmap bmp = null;
        private MemoryStream liveBitmap = null ;
        private int taux = 50;
        public Form1()
        {
            InitializeComponent();
 
        }
 
        private void button1_Click(object sender, EventArgs e)
        {
            bmp = WinLockBit.Properties.Resources.Koala;
            this.pictureBox1.Image=bmp;
 
            bitPerPixel = Image.GetPixelFormatSize(bmp.PixelFormat) ;
            this.label1.Text = bitPerPixel.ToString();
 
            nbBytes = bitPerPixel / 8;
            this.label2.Text = nbBytes.ToString();
 
            ApplyChanges(taux);         
 
            this.pictureBox2.Image = bmp;
           }
 
        private Bitmap TraitementImage(Bitmap bmp)
        {  
            Rectangle rect = new Rectangle(0, 0, bmp.Width, bmp.Height);
            BitmapData bmpData =
            bmp.LockBits(rect, ImageLockMode.ReadWrite,bmp.PixelFormat);
 
            // Get the address of the first line.
            IntPtr ptr = bmpData.Scan0;
 
            // MODIFICATION
            //generic : pour tout format de pixel .De plus utilse le stride ou ligne de numerisation
            int bytes = bmpData.Stride  * bmp.Height * nbBytes ;
            //int bytes = bmp.Width * bmp.Height * 3;
            byte[] rgbValues = new byte[bytes];
 
            // Copy the RGB values into the array.
            System.Runtime.InteropServices.Marshal.Copy(ptr, rgbValues, 0, bytes);
 
 
            // Set every red value to 255.  
            // MODIFICATION
            // si nbBytes =4 ce code doit revu (step à 4+ index de plus)
            for (int counter = 0; counter < rgbValues.Length - 2; counter += 3)
            {
 
                rgbValues[counter] = (byte)(rgbValues[counter] | 255);
                rgbValues[counter + 1] = (byte)(rgbValues[counter + 1] + 255);
                rgbValues[counter + 2] = (byte)(rgbValues[counter + 2] + 255);
 
            }
            // Copy the RGB values back to the bitmap
            Marshal.Copy(rgbValues, 0, ptr, bytes);
 
            // RAJOUTER
            bmp.UnlockBits(bmpData);
            bmpData=null;
 
            return bmp;
 
 
        }
        private void ApplyChanges(int taux)
        {
            ImageCodecInfo jpgEncoder = GetEncoder(ImageFormat.Jpeg);
            Encoder myEncoder = Encoder.Quality;
 
            try
            {
                EncoderParameters myEncoderParameters = new EncoderParameters(1);
 
                EncoderParameter myEncoderParameter = new EncoderParameter(myEncoder, (long)taux);
                myEncoderParameters.Param[0] = myEncoderParameter;
 
                bmp  = TraitementImage(bmp);
 
 
                liveBitmap = new MemoryStream();
 
                bmp.Save(liveBitmap, jpgEncoder, myEncoderParameters);
 
 
            }
 
            catch (Exception e)
            {
                MessageBox.Show(e.ToString());
            }
        }
 
 
        private ImageCodecInfo GetEncoderInfo(String mimeType)
        {
            try
            {
                int j;
                ImageCodecInfo[] encoders;
                encoders = ImageCodecInfo.GetImageEncoders();
                for (j = 0; j < encoders.Length; ++j)
                {
                    if (encoders[j].MimeType == mimeType)
                        return encoders[j];
                }
                return null;
            }
            catch (Exception) { return null; }
        }
 
        private ImageCodecInfo GetEncoder(ImageFormat format)
        {
 
            ImageCodecInfo[] codecs = ImageCodecInfo.GetImageDecoders();
 
            foreach (ImageCodecInfo codec in codecs)
            {
                if (codec.FormatID == format.Guid)
                {
                    return codec;
                }
            }
            return null;
        }
    }
}

bon code....