RAW conversion issue

[The Joker]

It is unclear to me what the aRGB profile is. I have never used it but have only ever seen it referred to RGB with an apha channel. Am I correct in this?
If it is an alpha channel and the A channel is not 100% then you will lose that when converting to jpeg since jpeg doesn't handle alpha channels.
Why you would use an alpha channel in a normal photograph I don't know. Its usually used for doing overlays or displaying semi transparent online and not in normal photo processing.
If aRGB is something else other than RGB with an alpha channel then please enlighten me. Do you really mean Adobe RGB, the terminology makes a difference to everyones understanding of it ?

[Patrick Gauthier]

It is unclear to me what the aRGB profile is. I have never used it but have only ever seen it referred to RGB with an apha channel. Am I correct in this?

I believe you are correct. I'm not sure why the sony nex would save the raw file with a transparency and have it less than 100%. That would be very sneaky of them. I'll have to double check when I get home, in my rush to post I may have indeed mixed up aRGB and adobe RGB.

Either way, whenever I export it as any file type other than .DNG (Adobe's RAW type format), I loose contrast in the darks and shadows. Even exporting as photoshops and lightrooms .psd format. So if there were a transparency, would it not be applied to a .tiff or .psd?

Patrick

[The Joker]

not sure about tiff but it should be saved in a psd. But why use an apha channel anyway? If you need one for graphics creation you can add one in photoshop later.
If you can, use Adobe RGB1998 or sRGB as output from camera. Adobe RGB1998 is probably better for colour images and sRGB is adequate for B&W but if you are capturing in colour which I expect you are, then use AdobeRGB1998 and desaturate in PS where you will have better control of it in a fully colour managed application. And when I say colour managed I mean an application where you can control your profiles regardless of B&W or Colour and not that your image is a colour image.
I think Peter had it right in the first place. And Maxotics has it right with reducing pixel depth too. It's a been a while since I messed with colour profiling.
jpeg is 24 but colour without an alpha channel.
If you do have an alpha channel then you can try exporting as tiff or 24bit png which can have alpha channel and is non lossy (unless you are converting from higher bit depth) but will create big file sizes. png is usually used for online display with transparency being adjustable.

[Patrick Gauthier]

It's all adobe RGB, from the moment the ARW file is imported. Not sure where aRGB was spawned in my mind, most probably my laziness in skipping 5 keys whilst typing.

[The Joker]

So keep everything in Adobe RGB then and don't convert or assign to other profiles.

So what you are seeing must be due to the convert from raw to jpeg. Jpeg is a 24bit file. So export to TIFF in high bit depth using adobe RGB 1998. Then open exported file in lightroom and see if there is a change. IF not then you will be sure its the convert to jpeg or rather 24bit that is causing the problem. If there is a visible change then you will be sure its the convert from raw that is causing the problem. But I would have thought decent software would show you the change before you actually export/save the file. Not having lightroom I can't test this.

Let us know for future reference.

[Patrick Gauthier]

Sorry for not posting this sooner.

As suspected, it's not a color profile issue, but it's also not a RAW conversion issue.

It's actually how the the presentation of blacks is influenced by the interaction between how lightrooms develop module re-sizes its previews and handles its "details" adjustments with the "fit" preview ("fit" previews the whole image). For those who don't use lightroom, the develop module is where you do all your editing, and the details panel controls sharpening and noise reduction. The develop module can't be avoided in terms of lightroom workflow - unless you only use presets.

The title of the thread is therefore a little misleading, as the issue is not directly with the RAW conversion.

Please see the two references from the adobe forum by trshaner - a very competent adobeist. ssprengle from the adobe forum was also very helpful.

https://forums.adobe.com/message/8817522#8817522

https://forums.adobe.com/message/7327718#7327718

From now on I will always preview the edited image in the Library module in lightroom, as the Library module "fit" preview more accurately represents the exported image. The most accurate way to deal with the issue is to work with 1:1 previews, as there is no re-sizing being done. However, a 1:1 preview is more technically useful than artistically useful, so that doesn't really help (you need to see the big picture - no pun intended).

It also doesn't matter if you do the editing with a RAW file or TIFF, the representation of the darks in the develop module "fit" preview will still be darker because there is still re-sizing taking place to see the whole picture.

In case you're interested, here is the image that caused this all.

https://www.flickr.com/photos/126831...blic/lightbox/