I’m afraid that would best be done with a Script that is linked to the opening event with File > Scripts > Script Event Manager.

The Script could be something like this (in this case it’s sRGB you may have to change that to the profile you prefer)

// 2012, use it at your own risk;

#target photoshop

if (app.documents.length > 0) {

var myDocument = app.activeDocument;

try {var theProfile = myDocument.colorProfileName}

catch (e) {

if (myDocument.mode == DocumentMode.RGB) {

// =======================================================

var idassignProfile = stringIDToTypeID( "assignProfile" );

    var desc3 = new ActionDescriptor();

    var idnull = charIDToTypeID( "null" );

        var ref1 = new ActionReference();

        var idDcmn = charIDToTypeID( "Dcmn" );

        var idOrdn = charIDToTypeID( "Ordn" );

        var idTrgt = charIDToTypeID( "Trgt" );

        ref1.putEnumerated( idDcmn, idOrdn, idTrgt );

    desc3.putReference( idnull, ref1 );

    var idprofile = stringIDToTypeID( "profile" );

    desc3.putString( idprofile, """sRGB IEC61966-2.1""" );

executeAction( idassignProfile, desc3, DialogModes.NO );

}

}

};

And in Script Events Manager the saved Script can be linked to the open-event.

Edit: And to avoid the dialog you would probably turn off the missing profile warning in the Color Settings.

Sorry, my suggestion #2 was wrong (my test file had unintentionally

sRGB embedded).

In order to avoid the Script solution, one may proceed as follows:

1. Color settings:    sRGB

2. Missing profiles: Don't ask when opening

3. Save:                   Check Embed profile (which is now sRGB)

The extra effort is nothing more than step No.3

Of course, if an image doesn't have an embedded profile, the best

guess is 'colorspace sRGB'.

Best regards --Gernot Hoffmann

When a file has no profile attached the basis of a conversion would be the Working Space; what good would that be if one does not know if that was the original space?

@c.pfaffenbichler Thanks! I understand.

@ssprengel Thanks but i'm studpid and i do not understand: if open an image with "leave as is" i do not assign a profile. But after this step i'm in photoshop with the image open (without profile) i can convert. Why i can not do this before?

@ssprengel Many thanks. Now i have understand.