Hi, I'm quite new to this so still learning. I have created a .PNG image but need to change it to a .JPG. However, when I do the quality is too poor and it's low resolution. The original .PNG is high resolution and you can see all the details of the flower even when zooming right in. Any advice on how to change the file type from a .PNG to a .JPG without losing the resolution would be appreciated. Obviously I need to change it to a .JPG in order to upload it. Thank you very much.
If you use Photoshop, set the maximum quality settings and do not reduce the size. But do you realise that Adobe Stock is looking for world class work from experienced commercial photographers? Your question suggests you may need more time immersing yourself in the technology before you're ready. Of course I haven't seen your work, and it may be very skilled, but the tech is a key part of what you need to know.
PNG is not a common file format for photos, so I wonder how you got to that.
PNG to JPEG: There are many programs that can do that for you, like Photoshop, but also Gimp or Xnview or similar. There should be no resolution loss or significant quality loss of your pictures if you choose a JPEG quality (compression quality) that is high enough. Maybe you show us how you converted the picture.
If you are new to stock, you should consider these resources: https://helpx.adobe.com/stock/contributor/tutorials.html
Please read the contributor user manual for more information on Adobe stock contributions: https://helpx.adobe.com/stock/contributor/user-guide.html
See here for rejection reasons: https://helpx.adobe.com/stock/contributor/help/reasons-for-content-rejection.html
and especially quality and technical issues: https://helpx.adobe.com/stock/contributor/help/quality-and-technical-issues.html
It sounds as if you had the settings to JPEG set to low quality/resolution. There shouldn't be a huge difference when converting from PNG to JPEG - only if the settings are low!
Have a look at this:
I would use Photoshop if you have it to convert.
There is also this online converter from Adobe: