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POIs this possible to compress a JPEG file with zip libraries
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copied!<p>As I know the jpeg file have a best compression ratio between another image extensions, and if I correct we can not more compress a jpeg file because that have best compression, so please help me about this. I create some jpegs as following:</p> <pre><code>ImageCodecInfo[] codecs = ImageCodecInfo.GetImageEncoders(); ImageCodecInfo ici = null; foreach(ImageCodecInfo codec in codecs) { if(codec.MimeType == "image/jpeg") ici = codec; } EncoderParameters ep = new EncoderParameters(); ep.Param[0] = new EncoderParameter(System.Drawing.Imaging.Encoder.Quality, _quality); using(MemoryStream ms = new MemoryStream()) { Bitmap capture = GetImage(); capture.Save(ms, ici, ep); } </code></pre> <p>And I zipped them with sharpziplib, in average every jpeg size is 130KB and after zip every file compressed to about 70KB, how it possible? there is just 2 answer I can Imagine.</p> <p>1- We can Compress Jpeg file with more compression ratio by zip libraries</p> <p>2- My jpeg file not correctly created, and we can create better jpegs (with more compression ratio as we can not more compress them with zip libraries)</p> <p>Does any one know about this? if we can create better jpegs please help me about it.</p> <p><strong>Edit:</strong></p> <p>this is my zip code to compress jpegs:</p> <pre><code>void addnewentry(MemoryStream stream, string pass, string ZipFilePath, string entryname){ ICSharpCode.SharpZipLib.Zip.ZipFile zf = new ZipFile(ZipFilePath); if(!String.IsNullOrEmpty(pass)) zf.Password = pass; StaticDataSource sds = new StaticDataSource(Stream); zf.BeginUpdate(); zf.Add(sds, entryName); zf.CommitUpdate(); zf.IsStreamOwner = true; zf.Close(); } public class StaticDataSource : IStaticDataSource { public Stream stream { get; set; } public StaticDataSource() { this.stream.Position = 0; } public StaticDataSource(Stream stream) { this.stream = stream; this.stream.Position = 0; } public Stream GetSource() { this.stream.Position = 0; return stream; } } </code></pre>

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