Picture size after export to small

[Ben346550176c5b]

I have a total of 4 images each of which has 3840x2160 pixels 72dpi. Each image has a memory size of 66MB. I have created a new empty area in affinity photo 2 with the dimensions 7680x4320 and inserted the 4 images. When I export this now it has 130 MB memory size. However, as each individual image has 66 MB, the new image should normally have a memory size of about 240 MB. The 4 individual images all have the same png file format, as does the exported image. Can you help me?

I have now tried this with Photoshop. If I change the bit png, think color run embedded and not. Nothing helps if I let the image in Photoshop under image larger info display customer there is the perfect size I want to have at export. When exporting it is larger than 100 MB.

[c.pfaffenbichler]

Not sure I follow. 

Could you please post screenshots to clarify? 

Are you complaining that the filesize is too small? 

Can you provide at least one of the four images? 

[Ben346550176c5b]

[D Fosse]

Both png and jpeg use compression algorithms to reduce file size. How much the size is reduced depends on a lot of variables and can be very unpredictable.

File size on disk generally means nothing and is nothing to worry about - except that jpeg compression is destructive and will degrade the file with every save. PNG compression is non-destructive.

Not sure why you need an image almost 10 000 pixels wide on the web, though. If this is not for web, don't use Export, Use Save As/Save a Copy.