Need help filling in all transparent pixels in this image

[winterludes]

Hi

I'm working on an image combining two images and i need to just fill in all the transparent pixles in the background layer.  I've tried suggestions here, but nothing has worked.  There must be a simple way to do this.  i wish photoshop had a "select transparent pixels" option.  

Here is a dropbox link to the file, maybe someone could do this for me really quick or tell me how?  it is not for profit, it is for an advocacy blog about the chronically sick homless people being thrown in jail.  

https://www.dropbox.com/t/4FGIyRCR5xEihBiq

Thank you!

[Semaphoric]

Try Select > Load Selection, and choose "Layer X transparency" for the source.

[winterludes]

This didn't seem to work, there are lots of areas of transparency still left.  Like this long rectangle in this screenshot.  

[Stephen_A_Marsh]

@winterludes 

I was going to suggest the same as @Semaphoric – yet another way, if the image has 256 or less unique colours, is to go to Image > Mode > Indexed Color and then edit the Image > Mode > Color Table... and edit the transparency swatch:

EDIT: If converting from RGB to Indexed Color, one can also bypass this step and directly convert by unchecking the transparency box.

[winterludes]

Thanks,

This looks like a cool idea but I'd have to merge all the layers to do it

[Stephen_A_Marsh]

Well, your file only has three layers, it's simple enough to dupe each layer to a new file and bring the data back in again to the layer – but I am just making a feasibility point.  :]

You could also put a solid color pixel layer behind the transparent layers and then merge down the transparent layer into the solid fill pixel layer.

[winterludes]

Ohhh your last sentence suggestion is sooooo simple and fixes the whole image in a second.  

I do want ot figure out how to select all transparent pixels in a faster way, it seems there should be an easy way to do this.  but this worked this time!  Thank you!  

[Stephen_A_Marsh]

You can CTRL/CMD click on the layer thumbnail in the Layers panel to load the transparency as a selection, which does the same thing as suggested by @Semaphoric 

[winterludes]

I've got a new very mysterious problem maybe photoshop has changed how layers are saved or there is some kind of bug ghost layer in my image.  Here is a screenshot of how the final image looks in photoshop.  And here is how it looks in preview in MacOS (and also in Topaz software).  This outline is from an old version of this image I made using a person sitting instead of lying down, which I will also attach and which is also missing layers in the final version.  

But with both images I have flattened the image and they do not look like this in photoshop.  

For some reason I've also been having trouble saving flattened images as pure jpegs.  They act like they still have layers and photoshop only gives me the few image formats that support layers as options for saving.  

What am I missing here?

I've attached 2 versions of this image that look way different in photoshop compared to how they save onto my computer.  

thanks everyone.  

[Stephen_A_Marsh]

Check your alpha channels. If you need them, don't delete them, use Save a Copy or enable Legacy Save As in your File Handling Preferences so that you can get to JPEG (which only supports flattened, 8bpc no alphas).