17 USC 106 states what are the exclusive rights of the copyright holder in the US:
the exclusive rights to do and to authorize any of the following:
(1) to reproduce the copyrighted work in copies or phonorecords;
(2) to prepare derivative works based upon the copyrighted work;
(3) to distribute copies or phonorecords of the copyrighted work to
the public by sale or other transfer of ownership, or by rental,
lease, or lending;
(4) in the case of literary, musical, dramatic, and
choreographic works, pantomimes, and motion pictures and other
audiovisual works, to perform the copyrighted work publicly;
(5) in the case of literary, musical, dramatic, and choreographic
works, pantomimes, and pictorial, graphic, or sculptural works,
including the individual images of a motion picture or other
audiovisual work, to display the copyrighted work publicly; and
(6) in the case of sound recordings, to perform the copyrighted work
publicly by means of a digital audio transmission.
If you actually copy the pictures and make the copies available via a link or similar technological means, that is infringement and providing an ancilliary link does not erase that fact. Fair use is not out of the question if you copy one image, especially if your usage is non-commercial research. You might endanger a fair use analysis if this is for-profit market research, unless the court finds your use highly transformative.
Copyright law does not prohibit "using" protected works, it specifically prohibits infringing on the copyright holder's exclusive right. Providing a link to a protected work is not the same as copying a work. However: (5) also gives the copyright holder the exclusive right to display a copyrighted pictorial work publicly. It seems that you propose to publicly display copyrighted pictorial work, which only the copyright holder has the right to authorize.
Still, US courts have not made it totally clear whether inline linking of images is legal. The case Goldman v. Breitbart finds that inline linking is infringing, contrary to (and in a different circuit from) the Server Test adopted in the 9th Circuit. In other words, this is not settled law in the US. It is also unsettled in Germany where infringement and not-infringement have both been found.