Converting web images into sRGB and also embedding the profile

Asher Kelman · Jan 9, 2010

Edit by CU: This technical discussion has been separated from this picture thread in the Photography as Art forum.

Just a reminder, folks: don't strip the EXIF and make sure that the © statement is in the IPTC statements. If you are lucky, Nestlé or someone else rich will use it! The other point is, ideally, a color profile should be embedded with the file, and generally sRGB for web use.

Doug Kerr · Jan 9, 2010

Hi, Asher,

Asher Kelman said:
]Just a reminder, folks: . . . and make sure that the © statement is in the IPTC statements.

Indeed, preferably in both IPTC forms , 'legacy" ("IIM", essentially an Exif extension) and "core" (XML based). (Some "viewing" applications will only read one or the other.)

Some applications, perversely, identify these as "IPTC" and "XML"! (even ExifToolGUI).

The other point is, ideally, a color profile should be embedded with the file, and generally sRGB for web use.

Remind me why that is useful if the color space is a standardized one, such as sRGB (and the image is tagged to show that).

Are we concerned that the displaying application will be sophisticated enough to deal with an embedded profile, but does not have the sRGB profile in its "library"?

Did you perhaps mean to recommend that generally the image should be in the sRGB color space, and be tagged to indicate that?

Thanks.

Best regards,

Doug

Asher Kelman · Jan 10, 2010

Doug_Kerr said:
Remind me why that is useful if the color space is a standardized one, such as sRGB (and the image is tagged to show that).

Are we concerned that the displaying application will be sophisticated enough to deal with an embedded profile, but does not have the sRGB profile in its "library"?

Did you perhaps mean to recommend that generally the image should be in the sRGB color space, and be tagged to indicate that?

Hi Doug,

The issue is that our software assumes sRGB and all numbers are mapped to that space. Often, the space is that of the camera or a wider RGB space and so colors are not seen as expected in other people's calibrated monitors. Color should be converted to sRGB and never just assigned to sRGB before sending it on the web.

Asher

Doug Kerr · Jan 10, 2010

Hi, asher,

Asher Kelman said:
Hi Doug,

The issue is that our software assumes sRGB and all numbers are mapped to that space. Often, the space is that of the camera or a wider RGB space and so colors are not seen as expected in other people's calibrated monitors. Color should be converted to sRGB and never just assigned to sRGB before sending it on the web.

Sure.

But why would we need to embed the sRGB profile? That is not the same thing as converting the image to be in the sRGB color space.

When we embed a profile, we are sending with the image a definition of the color space the image is recorded in (not just naming it), in case the displaying app never heard of that one.

Best regards,

Doug

Asher Kelman · Jan 10, 2010

Doug_Kerr said:
Hi, asher,

Sure.

But why would we need to embed the sRGB profile? That is not the same thing as converting the image to be in the sRGB color space.

When we embed a profile, we are sending with the image a definition of the color space the image is recorded in (not just naming it), in case the displaying app never heard of that one.

reread:

Asher Kelman said:
Hi Doug,

The issue is that our software assumes sRGB and all numbers are mapped to that space. Often, the space is that of the camera or a wider RGB space and so colors are not seen as expected in other people's calibrated monitors. Color should be converted to sRGB and never just assigned to sRGB before sending it on the web.

So it's pretty simple. Nothing to think about. Just convert to sRGB before sending it off and then embed that with the file.

Asher

Cem_Usakligil · Jan 10, 2010

Asher Kelman said:
So it's pretty simple. Nothing to think about. Just convert to sRGB before sending it off and then embed that with the file.

Hi Asher,

I think that there might be some slight confusion as there are three things here:
1) Converting the colors of an image into a color space (e.g. sRGB in this case).
2) Tagging the image as being in a specific color space, such as sRGB, so that any external application will know that it is sRGB rather than perhaps assume that it might be sRGB. In this case, only a tag for the color profile used is added to the image, not the color profile itself.
3) Embedding the color profile of an image in the image itself, which is the act of putting the technical characteristics of the color space of the sRGB profile into the image.

There is a good discussion about this subject here.

Cheers,

Tom Robbins · Jan 10, 2010

A motivated thief can clone out a copyright mark from a photo downloaded from the internet. This is probably a dumb question, but can such an individual (or corporation) also erase or alter the original IPTC statements?

Cem_Usakligil · Jan 10, 2010

Tom Robbins said:
A motivated thief can clone out a copyright mark from a photo downloaded from the internet. This is probably a dumb question, but can such an individual (or corporation) also erase or alter the original IPTC statements?

Unfortunately, yes it is very easy to do so. The copyright notice is not a protection, it is a warning sign which states that you claim to be the owner of this picture. If somebody else changes the IPTC and does the same using your picture, you may have to go to court to claim your rights. If my understanding is correct, you are strongly recommended to register the image copyright with the copyright office in the USA before going to court (for court cases to be handled in USA, that is).

So the wise thing to do is to never post a full sized picture on the net to start with. And if you cannot even stand the thought of somebody stealing your image (even when it is merely 400 pixels wide), then do not post at all. Otherwise, we all have to live with the consequences <sigh>.

Cheers,

Doug Kerr · Jan 10, 2010

Hi, Asher,

Asher Kelman said:
So it's pretty simple. Nothing to think about. Just convert to sRGB before sending it off and then embed that with the file.

Embed that what?

The process of tagging the file to show what color space is used is called "color space tagging". Is that what you mean? It is not called "embedding" of anything.

"Embedding" in this context refers to the matter of including in the file a complete description (not just the "name") of the color space in use.

Which do you have in mind? Once we know, we can recognize the proper way to describe it.

"Nothing to think about" is sure a dangerous observation (especially in this particular discussion, where clearly there is some serious ambiguity afoot).

"Nothing to think about: although the Moon is smaller than the Earth, it is farther away."

Best regards,

Doug

Doug Kerr · Jan 10, 2010

Hi, Cem,

Cem_Usakligil said:
Hi Asher,

I think that there might be some slight confusion as there are three things here:
1) Converting the colors of an image into a color space (e.g. sRGB in this case).
2) Tagging the image as being in a specific color space, such as sRGB, so that any external application will know that it is sRGB rather than perhaps assume that it might be sRGB. In this case, only a tag for the color profile used is added to the image, not the color profile itself.
3) Embedding the color profile of an image in the image itself, which is the act of putting the technical characteristics of the color space of the sRGB profile into the image.

Thanks so much.

In the more general, case, I would change your third item to read:

Embedding the color profile of an image in the image itself, which is the act of putting the technical characteristics (profile) of the color space in which the image is recorded into the image.

Best regards,

Doug

Tom Robbins · Jan 10, 2010

Cem_Usakligil said:
Unfortunately, yes it is very easy to do so. The copyright notice is not a protection, it is a warning sign which states that you claim to be the owner of this picture. If somebody else changes the IPTC and does the same using your picture, you may have to go to court to claim your rights. If my understanding is correct, you are strongly recommended to register the image copyright with the copyright office in the USA before going to court (for court cases to be handled in USA, that is).

So the wise thing to do is to never post a full sized picture on the net to start with. And if you cannot even stand the thought of somebody stealing your image (even when it is merely 400 pixels wide), then do not post at all. Otherwise, we all have to live with the consequences <sigh>.

Thanks Cem, I was afraid this might be so. Good thing including a copyright statement is as easy to do as it is.

Bart_van_der_Wolf · Jan 11, 2010

Doug_Kerr said:
Hi, Cem,

Thanks so much.

In the more general, case, I would change your third item to read:

Embedding the color profile of an image in the image itself, which is the act of putting the technical characteristics (profile) of the color space in which the image is recorded into the image.

Actually, it doesn't even have to be recorded in that color space. Just publishing it in that color space will do just fine ... ;-)

Cheers,
Bart

Asher Kelman · Jan 11, 2010

Bart_van_der_Wolf said:
Actually, it doesn't even have to be recorded in that color space. Just publishing it in that color space will do just fine ... ;-)

Cheers,
Bart

Bart,

That caught my attention, LOL! If the image is recorded in something other than sRGB, to get as close to the "same" appearance, one needs to convert the pictures color space by reassigning their numbers to what would be perceptually the same in the smaller sRGB space. Merely to publish a Profoto RGB created image in an sRGB print space would seem questionable. Aren't we supposed to always convert first?

Asher

Mike Bailey · Jan 11, 2010

Good conversation... In case it was overlooked in the heat of the moment, the link mentioned by Cem yesterday "good conversation about... here" was quite informative. It had comments by Andrew Rodney and even the late, great Bruce Fraser. So, if you haven't read it, it'd be good to backtrack for a moment and check it out.

Mike
____________________________

http://bluerockphotography.com

Bart_van_der_Wolf · Jan 11, 2010

Asher Kelman said:
Bart,

That caught my attention, LOL! If the image is recorded in something other than sRGB, to get as close to the "same" appearance, one needs to convert the pictures color space by reassigning their numbers to what would be perceptually the same in the smaller sRGB space. Merely to publish a Profoto RGB created image in an sRGB print space would seem questionable. Aren't we supposed to always convert first?

Hi Asher,

Yes, if we want to display colors like we intended them, we need to both convert (if not already in the output colorspace) to an output space (usually a generic one like sRGB if intended for the web) and preferably publish with the correct tag (or even embed the profile if it's not common) so that it can be displayed correctly in a colormanaged environment.

Cheers,
Bart

Doug Kerr · Jan 11, 2010

Hi, Bart,

Bart_van_der_Wolf said:
Actually, it doesn't even have to be recorded in that color space. Just publishing it in that color space will do just fine

I meant "recorded in the image that is published", not "recorded at the camera".

Probably "represented" would have been a better term.

When we "publish an image in sRGB", we of course mean that, in that image file, the image is represented under the sRGB color space.

Best regards,

Doug

Converting web images into sRGB and also embedding the profile

Asher Kelman

OPF Owner/Editor-in-Chief

Doug Kerr

Well-known member

Asher Kelman

OPF Owner/Editor-in-Chief

Doug Kerr

Well-known member

Asher Kelman

OPF Owner/Editor-in-Chief

Cem_Usakligil

Well-known member

Tom Robbins

Active member

Cem_Usakligil

Well-known member

Doug Kerr

Well-known member

Doug Kerr

Well-known member

Tom Robbins

Active member

Bart_van_der_Wolf

pro member

Asher Kelman

OPF Owner/Editor-in-Chief

Mike Bailey

pro member

Bart_van_der_Wolf

pro member

Doug Kerr

Well-known member