Making background level on images posted to web match background level in PI

[astrovienna]

How do I make the image I post to the web look the same as the image as I'm viewing in PI?  There has  to be a reliable method, but I've never found it.  The images I post frequently have different background levels than what I see in PI.  I've never had a problem getting colors to match, but the brightness is frequently problematic.  Is there a tutorial that explains this process? 

Kevin

[dave_galera]

What image formats do you post to the web, JPG or PNG?

[astrovienna]

JPG.  Is there an advantage to PNG?

[dave_galera]

PNG format is a lossless compression file format, which makes it a common choice for use on the Web. JPG format is a lossy compressed file format.
PNG gives a much wider range of color depths, including 24-bit (8 bits per channel) and 48-bit (16 bits per channel) truecolor, allowing for greater color precision, smoother fades, etc.

[pfile]

is it possible this is a color space problem? usually before uploading i do ICCProfileTransformation to bring the image in-gamut for sRGB. for a while i wasn't tagging the image with AssignICCProfile because astrobin seemed to have some problem with tagged images, but i'm told this is fixed now.

rob
 

[dave_galera]

Yes it looked like profiling problem but I wasn't sure how profiles are assigned or work in PI, I normally get it into ***

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[dave_galera]

Thanks Rob for the heads-up on AssignICCProfile and ICCProfileTransform, I will use it from now on as it has the ICC profile Adobe RGB 1998 which is perfect for me.

Kevin lets us know how you get on and if the problem is solved......

[astrovienna]

is it possible this is a color space problem? usually before uploading i do ICCProfileTransformation to bring the image in-gamut for sRGB. for a while i wasn't tagging the image with AssignICCProfile because astrobin seemed to have some problem with tagged images, but i'm told this is fixed now.

rob

Thanks for the help, Rob and Dave.  I'm not using either of those tools, and don't know what they do.  Let me define the question more clearly:  I'm viewing an XISF in PI, and I want it to look the same when I upload it (to pBase, in my case) and then view it in Firefox or another browser.  How do I make that happen?

Right now I'm just saving it as a JPG in PI and uploading it.  That often doesn't give me the same appearance, so I port a TIFF to PS and use Save to Web.  That usually works out, but not always.

Kevin

[dave_galera]

In color management, an ICC profile is a set of data that characterizes a color input or output device, or a color space, according to standards promulgated by the International Color Consortium (ICC). Look it up on the web there are lot of articles on it.

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Give it a try and let us know how you get on

[astrovienna]

Thanks Dave.  That worked in this case.  Is exporting it to PS necessary? I compared doing it that way with saving direct from PI, and at least in this case got the same results.  But I'm pretty sure I've been saving direct from PI (with the ICC Profile) and it wasn't always working out.  I'll have to keep a closer eye on the final result from here on out to be sure.

Kevin

[dave_galera]

In your case it is not necessary to export to PS if exporting direct from PI works for you....I just wanted you to do it this way just to prove that this was your problem, so now you can do it either way.

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Glad we got it resolved.....

[astrovienna]

Thanks Dave.  Just to make sure I have any other relevant settings correct, I've attached the settings I use for ColorManagementSetup and ICCProfileTransformation.  If anything there looks incorrect  to anyone, please let me know.

Kevin

[Juan Conejero]

Hi Kevin,

You are using your monitor profile (VA 2431 Series) as the default profile in PixInsight. This is usually a very bad idea because a monitor profile describes a device-specific color space, while you, unless there is a strong, sound and well-founded reason to proceed otherwise, want to work in a device-independent color space. Selecting your monitor profile as the default one is equivalent to saying "Hey, isn't it great, every image in the universe has pixel values representative of the way my monitor works". Unfortunately, this is not true

Your monitor profile should only be selected for the only purpose it has: as your monitor profile. Normally you should select the sRGB IEC61966-2.1 profile for both RGB and grayscale images. If you do this, then your final processed images will be WWW-compatible, that is, the default sRGB profile will describe them and they will work perfectly on any color managed web browser, even if you don't embed an ICC profile when you save your JPEG or PNG files.

You may prefer to work in a larger color space than sRGB, such as Adobe RGB for example, especially if you want to torture your images in terms of color saturation. In such case you can select the desired ICC profile as your default RGB profile. However, if you do this you'll have to use the ICCProfileTransformation tool to convert your images to the sRGB space before saving them as files to be deployed on the WWW, or on any device compatible with web color standards. Then you can also select the sRGB profile as your proofing profile. This will allow you to use the color proofing mode (Image > Color Management > Enable Color Proofing) to know how your image will look like when rendered on a web browser—if you see gamut warnings (flat gray areas) in proofing mode, then you know you've gone way too far with color saturation.

I hope this helps, let me know if you need more guidance. Color management can be tricky, but it isn't as complicated as people usually describes it. The key is simple: do not tell lies to the CM system. It always wins

[dave_galera]

Kevin,

There you go Juan has spoken, as you only upload to the web sRGB is OK for you, however, if you want to print from PS then always use Adobe RGB (1998) and then convert to sRGB for web uploads

[dave_galera]

Yes it looked like profiling problem but I wasn't sure how profiles are assigned or work in PI, I normally get it into ***

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Frightened of competition? LOL