Resize image without losing its quality/resolution in c#

Question

User-980333546 posted

Hi, I'm using code below to resize image but after resizing, we are losing image quality(resolution). 

Can someone suggest the best way to resize image without losing its resolution/quality?

 public string GetFixedSizeImage(string oldFile)
        {
            int sourceX = 0, sourceY = 0, destX = 0, destY = 0;
            float nPercent = 0, nPercentW = 0, nPercentH = 0;
            int height =1650, width=2350;
            
string fixedImageFilePath =@"OutputImagePath....";
 
try
            {
                System.Drawing.Image sourceImage = System.Drawing.Image.FromFile(oldFile);
                int sourceWidth = sourceImage.Width;
                int sourceHeight = sourceImage.Height;
                nPercentW = ((float)width / (float)sourceWidth);
                nPercentH = ((float)height / (float)sourceHeight);
              
                if (nPercentH < nPercentW)
                {
                    nPercent = nPercentH;
                    destX = System.Convert.ToInt16((width - (sourceWidth * nPercent)) / 2);
                }
                else
                {
                    nPercent = nPercentW;
                    destY = System.Convert.ToInt16((height - (sourceHeight * nPercent)) / 2);
                }
                int destWidth = (int)(sourceWidth * nPercent);
                int destHeight = (int)(sourceHeight * nPercent);

                using (Bitmap bmPhoto = new Bitmap(width, height))
                {
                    bmPhoto.SetResolution(sourceImage.HorizontalResolution, sourceImage.VerticalResolution);

                    using (Graphics grPhoto = Graphics.FromImage(bmPhoto))
                    {
                        grPhoto.Clear(System.Drawing.Color.White);
                        grPhoto.CompositingQuality = CompositingQuality.HighQuality;
                        grPhoto.InterpolationMode = InterpolationMode.HighQualityBicubic;
                        grPhoto.SmoothingMode = SmoothingMode.HighQuality;
                        grPhoto.PixelOffsetMode = PixelOffsetMode.HighQuality;

                        grPhoto.DrawImage(sourceImage, new System.Drawing.Rectangle(destX, destY, destWidth, destHeight)
                            , new System.Drawing.Rectangle(sourceX, sourceY, sourceWidth, sourceHeight), GraphicsUnit.Pixel);
                    }

                    ImageCodecInfo codec = ImageCodecInfo.GetImageEncoders()[1];
                    EncoderParameters eParams = new EncoderParameters(1);
                    eParams.Param[0] = new EncoderParameter(Encoder.Quality, 100L);
                    bmPhoto.Save(fixedImageFilePath, codec, eParams);
                    eParams.Dispose();
                }
            }
            catch (Exception ex)
            {
                throw;
            }

            return fixedImageFilePath;
        }
 

Answer 1

User-943250815 posted

There is no way to resize any image without loose.
If you reduce lots of pixels are discharged and conversion process does the best interpolating pixels, same if you enlarge lots of pixels should be created.
IMHO best you can do is play around with some Image Libraries that some resources like contrast, brightness, filters, etc. And what best fit in your case.
As a starting point https://imageprocessor.org/imageprocessor/