A good course image is critical to a course's success. It should grab the attention of the viewer and help them understand the essence of what the course has to offer. Following these simple guidelines will ensure that your course image is effective and impactful.
Please note: to avoid confusion, each Udemy course must have its own, unique image. The same image cannot be used for more than one course. Textual information such as the name of the course is not permitted within the course image. Please review the Use of Text section below for more information.
Image specifications
Always design your master course image at the following pixel dimensions. The main design needs to live within the content safe area for maximum visibility.
Minimum required dimensions: 750 x 422 pixels
Maximum required dimensions: 6000 x 6000 pixels
File format must be .jpg, .jpeg, .gif, .bmp, or .png
We recommend using the RGB color model while creating your course image, and not the CMYK color mode, since it is designed for computer screens and electronic devices
I-------------750 px------------I
Mobile crop area
Relevance
A good course image enables the viewer to predict what the course is about. Make sure that the image relates directly to the course content and is tonally appropriate.
Use of text
Do not include textual information or the name of the course within the image. You may use text in an iconic way such as a logo or product name related to the course. The image should have a main focus in the center, and the title should not overlay the photo and make the layout muddy. 
Stock photography
Stock photography can often feel staged, cold, or inauthentic. Only use stock images that feel natural and are high quality.
Color and contrast
Use colors that compliment one another and work well together. Opposite colors (red and green for example) can clash and cause visual vibration. Make sure there is enough contrast between the subject and background to ensure legibility.
Specify and simplify
One of the most important factors of a successful course image is simplicity. Use familiar visual concepts that communicate the course idea clearly. Try to feature iconic elements that capture the essence of the course in a simple, unique way.
Limit the number of visual elements and detail to drive better comprehension. Too many unique elements and too much visual detail will compete for attention and create confusion.
Use of illustration
Illustrations should be iconic and elemental rather than detailed or cartoony.
Foreground & background
Only use background images/patterns if they enhance or add to the comprehension of the course concept rather than repeating it.
Single point of focus
Incorporate a central point of focus in your images to draw viewers in.
Resolution
Images should be clear and non-pixelated.
Production
Avoid applying multiple visual effects or textures to your image.
Custom branding and the use of logos
You may use your own brand logo (John Smith, Inc) in your course. Make sure your logo is legible, on brand, has adequate negative space, and is within the content safe area. Do not add any frames, borders, strokes or letterboxing.
With regard to using someone else's brand (Apple, Microsoft, etc), consult your attorney and make sure all the content in your course complies with the Term of Service (in particular Section 6 "Specific Obligations of Instructors) :
NOTE: You will be responsible for all of Your Submitted Content, that You own or have the necessary licenses, rights, consents, and permissions, and have the authority to authorize Company, to reproduce, distribute, publicly perform (including by means of a digital audio transmission), publicly display, communicate to the public, promote, market and otherwise use and exploit any of Your Submitted Content on and through the Products in the manner contemplated by these this Instructor Agreement, and that no Submitted Content shall infringe or misappropriate any intellectual property right of a third party.