whats the best way to save an image as if sending it to someone for professional use? jpeg?

psd or tiff (uncompressed) IMVHO.

Avoid JPEG.  It is a lossy format do to its compression rate.  If you must use it, generate a high quality image which will mean a larger file size.

I think it all depends on what the final use will be. Your best bet would be to ask the recipient for their preferred file type and size.

I always save my render in psd format, after postwork you can save in many different format .

ok so it sounds like psd or tiff. thanks

png would do , it would be smaller than tiff , psd will preserve any layers

Professional end users usually want pdf for exact color printing.

Quote - Professional end users usually want pdf for exact color printing.

I'm not disputing what you say, I'm just wondering why it is so. I know that PDF can can include images, but I have always thought of it primarily as a text format, with its main advantage being cross platform compatibility of text. I also don't understand the "exact colour printing" bit, surely a TIFF or PDS  contains as much colour information as a PDF? Can you enlighten me further on these points.

Quote - Can you enlighten me further on these points.

A PDF does not guarantee exact color printing. It requires you to create it properly and the printer to have some clue about what to do with it for 'color precision' to be a realistic expectation.

PDF has many uses and is not really a 'text format'. It is used extensively in Graphics / Prepress / Printing because it pulls together all elements of the job into a single file: images, fonts and vector graphics are all embedded in the document.

As for saving images for file transfer, here's what I'd recommend:

1. get your image ready to go
2. convert it to LAB color, flattening if required
3. save as LZW-compressed TIFF

Why?

LAB color is device independent and purpose-neutral: it's the most straightforward method of providing color accuracy.

The way it encodes the image means that you will get more efficient LZW compression (which is lossless, don't forget).

But check that the person you're sending it to can handle LAB color images.

how would won know is he can handle LAB color images. i never even heard of a LAB image

Quote - how would won know is he can handle LAB color images. i never even heard of a LAB image

LAB is a color space, like RGB or CMYK. It's not a file format. It's supported only by EPS, PDF, PSD and TIFF file formats.

It's right there in Photoshop: Image>Mode>Lab Color. Might be under the Edit menu in versions earlier than CS2.

Most other decent image editing apps should support it, at least in more recent versions.

There's a quite terrifying explanation of LAB color here. Don't worry about all the formulae: Photoshop and the Adobe Color Engine (ACE) handle all this stuff for you.

LAB conversion has been a Photoshop standard for a very long time.  And I do imagine that other popular 2D programs are also equally equipped.