I am editing video in Premire Pro and have exported a still from some HD 1920�1080 footage as a Tiff file which looks excellent quality, as good as any rendered Jpeg from Lightroom from the Sony RX10. I have tried uploading the Tiff to SS and other sites that take Tiff but for some reason they do not recognize the format.

Is there a way to best get this still into a file that sites recognize by still keeping the quality ? I have tried looking for tutorials online but can't find anything that goes into detail of image quality. Premiere CC only gives the file formats options for exporting a still, not any quality.

I don't have Photoshop, only Lightroom. When I export from that as a Jpeg 100% quality, the file renders at only 1mb. If I render as a Tiff it renders at 11mb, larger than the source which is 7.9 mb

I tried uploading the new Tiff from Lightroom to SS and I got this message:

Pictures must be at least 4.0 megapixels. This picture is 1920 x 1080 = 2,073,600 pixels (2.1 megapixels).

I don't have Photoshop, only Lightroom. When I export from that as a Jpeg 100% quality, the file renders at only 1mb. If I render as a Tiff it renders at 11mb, larger than the source which is 7.9 mb

What is the question ? TIFF file size differences will be down to different output settings. Look at tiff compression algorithm used for output and whether the file us 16 or 8 bit (48 or 24). That JPEG file size is presumably the file size (ie closed) and not the image size.

Pictures must be at least 4.0 megapixels. This picture is 1920 x 1080 = 2,073,600 pixels (2.1 megapixels).

Yep. What is the question here ? That image size is big enough for iStock but not for Shutterstock according to the message. Which is not to say that the quality is necessarily good enough.