Steadman

Some comments. Rake w. grains of salt,
.GIF is a really old format, and can only offer 256 colors. Gradients must be dithered, and edge blending is likewise ragged. So simple forms w. a small number of colors are well suited for .gif. The format is 8-bit, and so tends to be small by contemporary standards.
.PNG was developed to replace .gif, but  accommodates up to 64-bit color depth. In images w. few colors, the .png routine can produce files smaller than .gif. But for images w. greater bit depth the files can become much larger. While ,png will ignore any colors not present, any of the million that are there will be recorded. The format us considered lossless. Add to that the space for transparency, and metadata, and the file size balloons. 
Also, at one time, the amount of computation necessary for the encoding was noticable. 
,JPG is considered lossy, although when the quality is set to 100%, it creates files of about the same size as .png. As compression increases, the routines average areas of color, and use methods that keep the image looking smooth to the eye. Lots of colors, and smooth smears for color gradations. Only at high compression that the artifacts become obvious. The artifacts will be there even for simple forms, so a highly compressed .jpg well not be so good for a geometric shape.

I think I understand, if so in Affinity just type the text, my example has black text, change the text layer blend mode to erase, this punches a hole through to the background, drag the text layer over the image until you see the shortened blue horizontal bar, I have placed a pink rectangle below the image to show the effect.

another list of free photos: http://platowebdesign.com/articles/free-stock-photos
 
creative commons search: https://search.creativecommons.org

Hey Everyone,
 
I have been using this site more and more recently: http://www.freepik.com/
Excellent quality vectors (imho anyway)
 
I also use this site for photo-based resources: http://www.freeimages.com/
(this site used to be 'stock xchng' if anyway remembers that)
 
I hope you find them useful :-)
 
--I did a search of the forum and didn't them mentioned so I apologise if these have been linked before--

photos: https://unsplash.com
 
some examples

I want to throw out there really quick that there's a good primer on managing stock vectors from Ezra at Affinity Revolution.
 
 

I am aware this is an old post but for those(like me) who have just obtained the program and have no idea about the artboards...(instead of automatically loosing your collage of concepts when you CTRL+N and POOF..GONE!) and wondering about artboards...

Artboards in my opinion of this fabolous software is the reason the name has been given "Affinity" - a similarity of characteristics suggesting a relationship, especially a resemblance in structure .   

Think of the artboards from a designer standpoint, artboards in tangible aspects is the blank white or black canvas Bob Ross buys and draws on.  But he also has other concepts of the same design so he pulls the translucent paper of his first artboard, sketches over it and grabs another artboard and lays his concept with updates "artboard2".. and so on and on.

I have found artboards to be very beneficial.  I no longer lose my designs concepts from the new document itself.  For some reason, when you start a new document and you have a current document and you never saved... it's a goner.  So I just start a fresh document and select the artboard tool and draw a nice size box to work in and create a few artboards just to put different designs on and I save it.  NOW I have multiple concepts under one roof.

Within each artboard pertains it's own dedicated projects and layers and so on that you would have with just a normal document.  So everything you do in "artboard1" stays within that artboard. Same for artboard2...3...4...etc.  So if you are designing a logo for a client and you have a mere 5-6 concept designs, you can design on one, copy and paste to the other and change it styles and so on and ALL of the artboards have their own independent projects pertaining the layers and everything.  I personally love it to death!.  I promise i never knew about it and was totally lost on the reason, until I kept losing my design projects with no way to recover.  So artboards are like mini "Affinity" apps running within itself.

I surely hope I made some sort of sense lol