In-camera it is balanced. In Sony Express Underexposed. Setting B&W points, and more

[JBW]

I consistently get chastised for underexposure and muddy shots. Undeniably I like a dark shot and there are times when my colours are muddy. But I am also having problems with my post processing. In camera this shot was balanced except for the blue which was underexposed. In Sony Express it showed seriously underexposed. This made setting the black and white points difficult.

When I moved to GIMP the blue was right off the scale and the rest was underexposed but not as badly. Setting B&W points was not nearly as futile. My final try at a better end product was to use PNG rather than JPEG.

Here is Sony Express after setting the B&W points and the other colours. But right from the start it was showing underexposed.

I moved it to GIMP using Tiff and it showed a very different histogram. So I again adjusted the B&W points

I may have found part of the solution. I have been exporting and uploading in JPEG. But as the two shots show, at least to me, PNG works better.
JPEG

PNG

[Stagecoach]

Brian,

Your in camera Histogram is produced from a Jpeg converted from the RAW file by the camera, it may not necessarily look exactly the same as the RAW file opened up in another programme. I do not see any evidence of 'serious' underexposure in any of those histograms shown.

With respect to the two images posted, jpg and png if I scroll between the two I could not honestly say I can see any difference. Ted of course will find something

[JBW]

Brian,

Your in camera Histogram is produced from a Jpeg converted from the RAW file by the camera, it may not necessarily look exactly the same as the RAW file opened up in another programme. I do not see any evidence of 'serious' underexposure in any of those histograms shown.

With respect to the two images posted, jpg and png if I scroll between the two I could not honestly say I can see any difference. Ted of course will find something

On my monitors the PNG is brighter and has more detail. But you are probably correct... let's wait for Ted to chime in.

[george013]

On my monitors the PNG is brighter and has more detail. But you are probably correct... let's wait for Ted to chime in.

You didn't mention with which image you started. Did you shoot RAW or JPG?
I had to look up PNG. It's another compression technique for images. Portable Network Grafics. Any compression on images is changing the image.

George

[JBW]

You didn't mention with which image you started. Did you shoot RAW or JPG?
I had to look up PNG. It's another compression technique for images. Portable Network Grafics. Any compression on images is changing the image.

George

I was shooting in RAW.

[george013]

I was shooting in RAW.

Don't forget: different RAW-converters will give you different results, different compression methods wille give you different results.

Your in-camera image is the result of the in-camera converter, using your camera settings.

George

[DanK]

The PNG looks only trivially different to me, and it is not really a solution anyway, as PNG is not as widely usable.

Like Grahame, I don't see evidence of underexposure.

I think the problem has to be the raw=>jpeg conversion in camera that is producing the histogram. I think in an earlier thread I mentioned that at least on Canon cameras, you can select a neutral or faithful image style to lessen this problem. The choice of picture style has no impact on the raw file, but it can lead to a less misleading histogram on the lcd. Can your camera do this?

[Round Tuit]

Brian,
I know nothing about Sony Express and very little about GIMP but, looking at your screen shots, my guess is that you are looking at different kind of histograms as you go from one software program to the next. When we talk of setting the black and white point, I believe that we generally refer to a linear RGB histogram. Gimp also show logarithmic histograms for "RGB", "Value", and each of the three color channels. You can also get "Luminance" histograms which are also different from RGB , Value or Brightness ones. Check the settings in your various programs to make sure you are comparing apples to apples.

Andre

[JBW]

Brian,
I know nothing about Sony Express and very little about GIMP but, looking at your screen shots, my guess is that you are looking at different kind of histograms as you go from one software program to the next. When we talk of setting the black and white point, I believe that we generally refer to a linear RGB histogram. Gimp also show logarithmic histograms for "RGB", "Value", and each of the three color channels. You can also get "Luminance" histograms which are also different from RGB , Value or Brightness ones. Check the settings in your various programs to make sure you are comparing apples to apples.

Andre

I will keep this in mind.

[JBW]

The PNG looks only trivially different to me, and it is not really a solution anyway, as PNG is not as widely usable.

Like Grahame, I don't see evidence of underexposure.

I think the problem has to be the raw=>jpeg conversion in camera that is producing the histogram. I think in an earlier thread I mentioned that at least on Canon cameras, you can select a neutral or faithful image style to lessen this problem. The choice of picture style has no impact on the raw file, but it can lead to a less misleading histogram on the lcd. Can your camera do this?

I did try your suggestion but could find no way to do it with the Sony Alpha a58

[JBW]

Don't forget: different RAW-converters will give you different results, different compression methods wille give you different results.

Your in-camera image is the result of the in-camera converter, using your camera settings.

George

will remember.... probably

[Manfred M]

Brian - the Sony Express screenshot you provided suggests that the software is really a version of Phase One Capture One (which I use). Phase One and Sony appear to have a close working relationship, so I suspect that the basic engine and software are identical in both pieces of software.

I grabbed a histogram from it and compared it to a histogram of the same image using the Photoshop / Lightroom histogram and the two appear to show identical output.

I don't have Gimp running on my computer, so I can't comment on it.

[Stagecoach]

I did try your suggestion but could find no way to do it with the Sony Alpha a58

Brian, with respect to Dan's suggestion and picture style affecting the histogram viewed on the camera if you look at page 134/135 of your manual Sony call it 'Creative Style' and it appears you have identical options we see on NikCanOns.

[JBW]

Brian - the Sony Express screenshot you provided suggests that the software is really a version of Phase One Capture One (which I use). Phase One and Sony appear to have a close working relationship, so I suspect that the basic engine and software are identical in both pieces of software.

I grabbed a histogram from it and compared it to a histogram of the same image using the Photoshop / Lightroom histogram and the two appear to show identical output.

I don't have Gimp running on my computer, so I can't comment on it.

it is the same program but restricted to Sony cameras. it is also a slightly stripped down version as it is the free one.

[JBW]

Brian, with respect to Dan's suggestion and picture style affecting the histogram viewed on the camera if you look at page 134/135 of your manual Sony call it 'Creative Style' and it appears you have identical options we see on NikCanOns.

Creative style is set to standard. I don't know where you found such a big manual mine only has 95 pages.

[george013]

I've been examining your Gimp histogram and the shown channel is "value".
Beside that different converters and different compression methodes give different results, you should also compare those without further editing and with the same settings of the histogram.

From the Gimp tut

In GIMP, each layer of an image can be decomposed into one or more color channels: for an RGB image, into R, G, and B channels; for a grayscale image, into a single Value channel. Layers that support transparency have an additional channel, the alpha channel. Each channel supports a range of intensity levels from 0 to 255 (integer valued). Thus, a black pixel is encoded by 0 on all color channels; a white pixel by 255 on all color channels. A transparent pixel is encoded by 0 on the alpha channel; an opaque pixel by 255.

For RGB images, it is convenient to define a Value “pseudochannel ”. This is not a real color channel: it does not reflect any information stored directly in the image. Instead, the Value at a pixel is given by the equation V = max(R,G,B). Essentially, the Value is what you would get at that pixel if you converted the image to Grayscale mode.

If you want to know how far the camera-settings are influencing the converter/post editing you could take a B/W picture in RAW and find out what happens in difference converters. I know the result for Nikon, not for yours.

George

[Stagecoach]

Creative style is set to standard. I don't know where you found such a big manual mine only has 95 pages.

I found it on the Sony PDF manual download site, titled Sony Alpha A58 so assuming it's the right model. This one has 215 pages

It also mentions that Contrast, saturation and Sharpness can be independently adjusted for each of the separate 'Creative Styles'.

[JBW]

I found it on the Sony PDF manual download site, titled Sony Alpha A58 so assuming it's the right model. This one has 215 pages

It also mentions that Contrast, saturation and Sharpness can be independently adjusted for each of the separate 'Creative Styles'.

if you could get me the url for that dl i would sure appreciate it cause I can't find it.

[Stagecoach]

if you could get me the url for that dl i would sure appreciate it cause I can't find it.

Brian,

It was the one at the top of the page I downloaded called 'Handbook' and has a file size of 2.7 Mb when downloaded. I did not look at any others to see if there was any difference.

https://www.sony.co.uk/support/en/co...n/SLT-A58/list

[JBW]

Brian,

It was the one at the top of the page I downloaded called 'Handbook' and has a file size of 2.7 Mb when downloaded. I did not look at any others to see if there was any difference.

https://www.sony.co.uk/support/en/co...n/SLT-A58/list

I have died and gone to heaven! This is identical to the manual I already have up till page 76 then it goes into advanced stuff. I have a lot of reading and experimenting to do. Thanks!