Pixalated png after import

[Inge225195940869]

Hi all, 

Whenever I try to import a png, the image becomes pixelated in Illustrator. When you in check a photo viewer app these pixels are not visible yet. It's unfortunate that a 'good' picture is no longer usable after placing it in Illustrator. What can be the problem here? I use the latest version of Adobe. The raw data is opened and processed in ImageJ, next exported as png.

I already did the following things: 

- Tried it on (different) Windows desktops and MacBook 

- Uninstalled the latest version and tried an older version

- Reset preferences

- Imported the png via 'place' via 'open' via dragging

- Exported the image as tif or jpeg

Ofcourse, I can be due to the quality of the png image or the raw data, but when checking a photo viewer or using it for a presentation in powerpoint, the image is not pixelated and perfectly usable. 

I found this question online a couple of times but nobody was able to come up with a solution then, so fingers crossed.

Thanks! 

[Monika Gause]

Please show a screneshot

And please tell us the effective resolution of the image.

[Inge225195940869]

According to photoshop, the resolution of the resolution is 72 ppi, image size is 167 px x 170 px.

I included a screenshot where I didn't change the size of the image. I placed it in Illustrator and zoomed in. The photo is more pixelated than in the photo viewer app. I want to make a scientific figure with several panels of confocal images, so it is important that readers/reviewer can zoom in on certain images. 

In the meantime, I tried changing the resolution to 300 ppi in Photoshop and this seems to do the trick? However, I was wondering if there is anything else I can do, except going via Photoshop or maybe starting taking the raw data at a higher resolution to begin with (this is not an option anymore, because we have to redo experiments then). It's just weird to me that a photo that is perfectly fine changes that much in Illustrator. I am aware of the raster to vector change but still!  

[Inge225195940869]

Sorry, the screenshot is not showing my point at all. Hopefully this one is better!

[Monika Gause]

What Ton days.

PNG is a pixel image. And your image is tiny.

[Bill Silbert]

What always must be remembered with raster images—size is the most important factor when using them. Even an image with a high actual resolution will lose quality and show pixelization when it is enlarged. So what is always important is the effective resolution which is the resolution an image becomes when it is enlarged. For example a 300 ppi (actual resolution) image at 100% will only have an effective resolution of 150 ppi when it is enlarged to 200%. Size matters.

[Inge225195940869]

Thank you. That makes sense. I was just puzzled why there was such a big difference between a png and a png when exported in illustrator. I opened the png in photoshop and changed the ppi to 300, this yields a png I can import into Illustrator without it becoming pixelated. 

[Bill Silbert]

When you say that you changed the ppi to 300 did you do it by just "upping the number" with "Resample" checked (first picture below) or with "Resample" unchecked (second picture)? If your answer is the first way then you have not actually made the image into a higher "real" resolution but rather Photoshop has "calculated" fill-in pixels that may or may not give a clean result. If your answer is the second then the dimensions of the image will be reduced as the resolution you entered is increased. The second way will not actually help with enlargements but I have seen that using the second method and entering the dimensions that the image will be used at does seem to give a better viewing result when importing into Illustrator or InDesign.

[Ton Frederiks]

I would not expect much better from a 72 ppi 167 X 170 px image zoomed in at 400%.

[Inge225195940869]

Yes, indeed. However, the zoom seemed okay when the image was not imported into Illustrator. Therefore I was hoping I just missed something while importing for example. I am aware the picture is not ideal at all, but retaking it at 2048x2048 is unfortunately not an option anymore, so I was trying to make it work!