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object photo = feature.Value[blobFieldIndex]; IRasterExporter exporter = new RasterExporterClass(); var rasterAsBytes = exporter.ExportToBytes(((IRasterValue) photo).Raster, "TIFF"); IMemoryBlobStream memBlobStream = new MemoryBlobStream(); var varBlobStream = (IMemoryBlobStreamVariant) memBlobStream; varBlobStream.ImportFromVariant(rasterAsBytes); var tableAttachments = (ITableAttachments) featureClass; var attachmentManager = tableAttachments.AttachmentManager; attachmentManager.AddAttachment(feature.OID, new AttachmentClass { Name = "nameOfRaster.jpg", ContentType = "image/jpg", Data = varBlobStream });