[JAI IMAGEIO] TIFF to JPEG Loss DPI, HOW TO?

Question

Hi!
I tried to convert a tiff image to jpeg with the same dpi resolution but i don't know how to make it or if i'm on the right way.
Here is my code.
Thanks for your help!
public static void convertFromTifToJpgPrim(String sSourceFileName, String sTargetFileName) throws CoinDatabaseLoadException, SQLException, NamingException{
try
RenderedOp renderedOPCrop = JAI.create("fileload", sSourceFileName);
RenderingHints qualityHints = new RenderingHints(RenderingHints.KEY_RENDERING,RenderingHints.VALUE_RENDER_QUALITY);
RenderedOp renderedOPScale = JAI.create("SubsampleAverage",
renderedOPCrop,
new Double((double)0.5),
new Double((double)0.5),
qualityHints);
JPEGEncodeParam jpgparam = new JPEGEncodeParam();
jpgparam.setQuality(1f);
FileOutputStream fs = new FileOutputStream(sTargetFileName);
ImageEncoder enc = ImageCodec.createImageEncoder("jpeg", fs, jpgparam);
enc.encode(renderedOPScale);
fs.flush();
fs.close();
catch(Exception e)
e.printStackTrace();
}Regards,
Julien

Answer 1

I don’t see much difference in the side-by-side thumbnails.  The JPG’s histogram (right one) has a little more black bunched up on the lefthand end and the histogram is vertically scaled to make that higher peak fit so the entire rest of the histogram is shorter, but the entire JPG’s histogram is not shifted left (toward the dark end) very much at all.  Specifically there is a red peak in between the f/11 and 5.0sec indications on both and the green peak is above the 10mm in both cases.  Converting to sRGB will clip things to fit within the sRGB gamut so some difference is expected, I’m just not seeing very much.  Are you seeing more of a difference in Finder/Preview than with the re-imported JPG in LR?
You could try exporting your TIF as a ProPhotoRGB JPG and re-import that to compare histograms, since LR’s internal workspace is a wide colorspace like ProPhotoRGB is.
If you think you have accidentally changed something in your LR preferences, you can exit LR and delete the preferences file (or move it somewhere) then restart LR and let it rebuild a new one.  Before doing this you might want to review your LR preferences in case there’s something important that needs set back.
http://helpx.adobe.com/lightroom/kb/preference-file-locations-lightroom-4.html