Convert jpg image from rgb to cmyk

The correct workflow is to optimise your images in Photoshop (straighten, color correct, sharpen etc), keep them in RGB color mode, ensure the resolution is around 300PPI in the size you'll be printing them at in InDesign.

Place the images into your InDesign document, where you can add the text, color panels etc. Double check in the Links panel that each image has an effective resolution of between 200 and 300PPI, and there are no errors in the pre-flight.

Also ensure that those images that bleed do so. Unless you've been given a spec by your printer select from the InDesign presets, PDF/X-4. Export as Pages (not Spreads) tick Use Document Bleed Settings and Crop Marks. (This PDF will convert to CMYK).

Christian, the printing ink gamut of color is smaller than your RGB gamut and when color is critical in lithographic reproduction, an additional color plate is often used (at an additional cost, of course) to meet the demand.

In addition, converting RGB to CMYK without knowing the lithographer’s  print profile is risky business and is probably not giving you an accurate preview. I suggest you leave the conversion to the lithographer and request a proof  (in the US it is often referred to as a Contract Proof). Base your decision and options on that.

Litho Ink: Regarding the ability of yellow to absorb B light, the magenta’s ability to absorb G and cyan’s ability to absorb R --in my experience I have found that usually Yellow does a fine job, magenta less so, and cyan is the weakest in the triad. So, in your case, the M is limiting orange match. If it is grayish, check the amount of C.

Cosmetics offer a great challenge and extra plates (called touch plates or kickers) are used -- extras such as peach, warm gray and special reds. Regarding Cyan, if you were to dip an ink knife into a can of cyan and.draw it down to its lightest ink layer, you will see it go.toward gray.

Oh, one more thing regarding the appearance of color saturation and contrast : discuss a varnish pass with your lithographer.

Some colors in an RGB image may forever be out of gamut for some or even all commercial CMYK Spaces, but maybe these pages can provide a Color Management introduction:

Understand Photoshop color management

COLOR MANAGEMENT PHOTOSHOP CC CS6 Basic ColorManagement Theory ICC Profiles Color Spaces Calibrated Monitor Professional…

Is there any possibility to convert this images without any colour changement?

As you fail to mention both the involved RGB Space/s and the CMYK Space I assume you have little idea about Color Management and you may want to read up on it.

Some RGB Spaces can be almost completely represented in some CMYK Spaces, others even less so.

So what are they?

In general it is perfectly acceptable to place profiled RGB images in a page layout application like Indesign and separate on pdf export, so you may be wasting your time trying to convert the images before placing them.