# TIFF vs DNG



## PeterG

I have seen a number of discussions as to the benefits of either TIFF or DNG but am still unclear as to which is most appropriate. I am going to be scanning a large number of slides using SilverFast scanning software to scan and manipulate. Then storing and editing in Lightroom and editing where necessary in Photoshop. Is it better to use TIFF or DNG?


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## Johan Elzenga

For scans I would use TIFF. I see no benefits in using DNG for this.


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## clee01l

DNGs are based upon the TIFF/EP6 Standard. So, DNGs are all TIFFs, but not all TIFFs are DNGs. TIFFs are always storing the image data as RGB elements. DNG has a little more flexibility in how it treats the image data block.  RAW image data recored by the camera sensor is not RGB and needs to be de-mosaic'd and converted to RGB before processing engines like LR can work with the data. DNGs holding RAW data can keep the data as mosaic'd and non-linear. Or it be converted to RGB and stored as RGB. RGB data is not a RAW data structure. TIFFs on the other hand, Always store image data as RGB data.
Now, if you are scanning analog slides, the scanning software will most likely create RGB data.  So in that case, it matters little whether your data has a TIFF wrapper or a DNG wrapper.  All (almost all?) image processing software can handle the TIFF format.  Some image processing software apps do not support DNG format or all flavors of DNG.  For this reason it is better to save your scans as 16 bit compressed TIFFs.


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## Johan Elzenga

Agreed. One word of warning about compression: if you use 16 bits/color, the traditional LZW-compression in TIFF is pointless. It often even creates bigger image files! Use ZIP-compression, or no compression at all.


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## johnbeardy

For me the crucial advantage of saving as DNG in this situation is that you can't save over the file. So you'll not open a TIFF in Photoshop, do a load of clumsy edits or downsize for emailing or web or whatever - and then save those edits back into the file. With DNG, all your cleaning up will be as non-destructive as if you've been editing a raw file.


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