CR2 thumbnail image is darker

I am a amateur bird photographer , I tried DxO pureRAW 1.2 for several days, the performance of denoise is excellent .
but I found some ploblems as below .

  1. when input CR2 RAW file , if you look at the thumbnail image , some are darker , some are normal , I wonder this is a bug , I can sent CR2 RAW file to you if you need it .
    CR3 is OK to me , CR2 unstable (both 1D4 and IDX2).
  2. once “DxO modules” button become “No actions required” , it can not change setting again . I try to press “DxO modules” button but it does not working .

Computer system : Windows 10 with i5 CPU

Camera :

Lens :
500mm / F4.0
600mm / F4.0

Wei-Hsin Chen

Welcome to the forum, @Wei-Hsin-Chen !

Previews of RAW files often look different if viewed in explorer, finder or applications - each OS and application projects the previews differently:

  • Some present the thumbnail or preview that is embedded in the RAW file
  • Some apply colour profiles, exposure compensations, sharpening and whatnot

While it might be tempting to regard one as right and the other as wrong, the most important thing imo is that the processed image looks like what you intended it to look like, be it on a screen or as a print.

Note that PureRAW does not offer any possibility to change general settings. It is meant to be a pre-processor for whatever app you use to finish your images in.

thank you for quickly reply .
my concern is not only thumbnail , the image of DNG file is also darker .
after “process RAW phot to JPG or DNG” , no matter you choose “view results” or “export to Photoshop” ,
the image always darker .
my ploblem is some image is darker and some is normal , below are my examples :
first , normal

second darker

I have another question about DxO module button , my question is I want to remove Dxo module setting , but can not enter the menu .

Wei-Hsi Chen

You are using Photoshop to compare the images. Photoshop will treat different files differently, depending on the image content.

You cannot rely on any processed image looking like the “original”, especially with RAW files where, what you are actually seeing is an embedded, processed, JPEG version of the RAW data

DxO modules are not normally available for generated DNG files, only on original camera RAW and DNG files

Let’s compare to DPP 4.0
as you can see below the problem is the same , some CR2 is normal , some CR2 is Darker



Of course. That is because it is not the software that is producing the images that is at fault, it is the fact that they are two different image file types and Photoshop is interpreting them differently.

Have you tried a different viewer to compare them?

@Wei-Hsin-Chen, you are right, the images look different.

I also think that we have to accept the fact that it is as it is.

For me, such differences don’t matter. They are simply different expressions of the same thing. Like some people will say that a glass is half empty, while others will say that it is half full and a few might even say that it is filled to the brim - with water and air.

If I don’t like the expressions as delivered by the camera or raw converter, I’ll use my image editor(s) and make them look the way I want them to look - exercising my artistic freedom.
Why else would I post-process?

There are many bird’s color is black , darker image from Dxo pureRAW will lost their detail , so I can not accept darker image after any denoise firmware.
I do like Dxo PureRAw’s denoise result , better than “Neat Image” which is my currently denoise firmware .
in my opinion this is a firmware bug , I can sent my RAW file to your engineer for debug if necessary.

Wei-Hsin Chen

I know there is a embedded JPG inside the RAW , and that is for image viewer to speed up display on the screen .
normally I use BreezeBrowser or FastStone for my image viewer , the image’s brightness are all the same like I seeing in the camera’s LCD screen .
the image I posted above are all RAW file .
I use DPP and PHOTOSHOP to process RAW .

Wei-hsin Chen

Wei-Hsin Chen

If other software shows them as having the same brightness, the it has to be Photoshop that is showing them differently.

Please post an original RAW that you have issues with. Use a sharing service if the file is too big.

A digital camera has a utility containing some output settings. You can adjust several parameters that are used in the in-camera conversion to a RGB raster image. DPP, Canon, is using those in-camera parameters too in it’s conversion. Other converters are not using these parameters. So what you see is difference between a raw conversion using the in-camera selected parameters and a raw converter that’s using it’s own parameters.
You can make that visible by setting the camera to monochrome,B/W, and do the same comparison. The result in DPP will be a monochrome image, in another converter a colored image.
You might also see that the histogram is not the histogram of the embedded jpg but the histogram of the converted image.
I speak based on my knowledge of Nikon, but I don’t believe it’s different for other brands.
Image viewers do use the embedded jpg.


I’ve been birding for 11 years .
I only take RAW , and use DPP and Photoshop for RAW processing .
this is the first time I saw a darker image from APP .
if DPP / Photoshop can get the correct data from RAW file , there is no reason Dxo PureRAW can not do it .
that’s why I think it’s a software bug
BTW , CR2 is a very common RAW format for Canon camera , 5D2 /7D2/…1D4/1DX/1DX2 …

Wei-Hsin Chen

I post 3 RAW
1 is Normal , 2 are Darker
DxO Normal-Pitta.CR2 (20.7 MB)
DxO Darker 1-Purple Swamphen.cr2 (23.8 MB)
DxO Darker 2 - Chestnut Munia.CR2 (19.4 MB)

Wei-Hsin Chen

I opened them in PL4 and they are darker. I don’t know what setting PureRaw is using, I don’t have it, it’s included in PL4.
Read what @platypus wrote

Two exampels of a conversion in PL with no-correctioon and standard-correction.

The other two have less differences so I think it’s based on the image itself too.

In fact, what you are seeing is the difference between the embedded jpeg in the CR2 file and the DNG file.

If I open the CR2 files in PL4, the first thing I notice is that the “DxO Darker 1-Purple Swamphen.cr2” file was taken with a lens that DxO do not have a module for. But this isn’t going to affect the overall dark/light appearance. The other two have a supporting module.

If I now export it to DNG with just the default optical corrections for the DxO lens module lens and DeepPRIME NR, in PL4, I can’t see any noticeable difference.

The CR2 file…

The DNG file…

This is because, in PL4, for the CR2 file, you are looking at the demosaiced image and not the embedded jpeg, which is what you see on the back of the camera.

However, if I then using macOS Quick Look to view the images…

There is a noticeable difference, with the CR2 on the left.

Unless you are using a demosaicing application to view the CR2 files, you will only ever get the jpeg preview, which has already been processed in the camera.

Now, I made a virtual copy and couple of minor adjustments to it in PL4 (Smart Lighting and a slight tone curve)

… and re-exported to DNG.

Now, in macOS Quick Look, I get…

With the CR2 on the left and the DNG on the right.

I will repeat - if you are not using a demosaicing too like PL4, the preview you get from th eCR2 file will always be the embedded, processed, jpeg. And it would seem that Photoshop is showing you exactly that.

When they are opened in any demosaicing tool, RAW files hardly ever look like their jpeg thumbnail.

And I can do the same with the Swamphen image…

Again, CR2 on the left, DNG on the right

DPP is a demosaicing tools. And it uses the in-camera settings so the result of the demosaicing is exactly the jpg. Any other brand converter will/can not use the in-camera settings but all show the converted RGB raster image. Also Photoshop.

Except in their native converter. DPP for Canon, CaptureNx for Nikon, the others I don’t know.


Indeed, which is why the preview of the CR2 looks so good. But, for the DNG file, it is taking the results of an export of the unprocessed RAW CR2 file, which is not going to include any such “pre-processing”


DxO is definitely doing something to the Swamphen:

Left image: Preview as extracted from the file with exiftool (check command above the image)
Middle: DxO PhotoLab with “No Correction” preset. (“Landscape Neutral” will be closer to preview)
Right: Adobe Lightroom Classic

Adobe’s representation is close to the embedded preview and that is what Adobe aims for with its default settings. DxO does it’s own thing, which leads to the darker preview.

@Wei-Hsin-Chen, I recommend that you create a bug report and add the images to the report, so that DxO can check out what is going on.

I’m not sure if this really is a bug in PureRAW, you get exactly the same kind of result if you open the file in PL4 and do a straight export to DNG with only the optical corrections and DeepPrime.