From webcam to greetings card

[William Overington]

Firstly I know very little about scaling images, so it is possible that my concerns are groundless.

The issue is this. I am using Affinity Designer for this particular purpose, but the question is of use for other projects with other Affinity Software too.

I have found that there are a pair of very nice webcam feeds from a station, in fact a present terminus, on a heritage railway line. The second one is perhaps more interesting usually, but the different angle relative to the track on the first one is good in some circumstances.

https://www.ipcamlive.com/broadway1

https://www.ipcamlive.com/broadway2

No trains today, but there are planned to be over the weekend.

https://www.gwsr.com/planning_your_visit/what_to_see_and_do/locomotive_roster.html

https://www.gwsr.com/

The railway is single line, but with two tracks at a few places, as here.

Trains arrive from the right of the picture and on the track next to the station building. If the train is locomotive hauled, the locomotive goes beyond both cameras, is uncoupled and runs round the train so that it can pull the train back the other way. If the train is a railcar set then the driver goes to the cab at the other end, so no uncoupling or run round.

For background information in case you might like to go virtual trainspotting,

https://www.gwsr.com/planning_your_visit/visiting_gwsr/2021_Calendar_and_Timetables.html

https://www.gwsr.com/planning_your_visit/what_to_see_and_do/locomotive_roster.html

However, the issue here is that I can get a Print Screen image from the webcam and I can use it to make a greetings card using the Papier facility and I can then frame the greetings card in a frame from Tesco delivered with the grocery.

So all done from home.

The issues is that the webcam image does not have the same pixel size as needed for the greetings card, nor indeed the same aspect ratio.

So either I get all the picture and some white space on the card, or I get to fill the card yet lose some of the picture, or I lose some of the picture and also get some white space.

The webcam can be set to full screen view, which on my computer gives a Print Screen image that is 1366 pixels by 768 pixels, so 16:9 which is an aspect ratio ofabout 1.77 to 1.00

The images for the greetings card is 2171 pixels by 1571 pixels which includes bleed areas, so giving a card 7 inches by 5 inches with 3 millimetre bleed areas, so an aspect ratio of about 1.38.

Maybe it is not the best way to do it, so I am open to advice, but I have been pasting the Print Screen image from the clipboard into Microsoft Paint and saving as a png file with the locomotive number, the date and time and possibly a bit of extra information, such as stationary or in motion all in a long file name so as to know which image is which..

So I start with a blank canvas of 2171 pixels by 1571 pixels at 300 dots per inch and I place the png image onto the canvas and then centre it on the page.

So I could have that as the finished artwork, produce a jpg image, upload to the template at the Papier webspace, add some information about the image, locomotive, place, date, time, other as I choose where the greeting goes, one can change the font to Garamond, black, letter spacing 1.0 and it looks very different from the placeholder text.

https://www.papier.com/landscape-photo-313

There is a Customise button that takes one to a blank canvas, one can upload a jpg file. Notwithstanding the advertising as a photo card and to send the card to someone else as a greetings card, it is possible to use a jpg file of artwork, and send it to oneself as an art print for framing.

The issue that I am asking about is what if I want to scale the card to get a larger image. Previously, both with a picture from the webcam and with artwork I have only scaled by exactly two times or exactly by three times. I know that that can make it blocky but I wanted some prints of bitmap artwork from many years ago and it was risk blocky or go without, but, whilst recognising that I do not have expertise in assessing printed images, from my hobbyist artist standpoint, the prints that I got look very good.

So what I am concerned about is if I scale by some real number, such as 2171 divided by 1366, which is 1.589, will I get sort of funny effects in the print due to rounding or whatever it might be called? What scaling is considered sfe and what is not if starting with a bitmap image please?

That way I can choose the best scale to balance getting a good picture to frame against losing some of the detail around the edges.

William

 

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[walt.farrell]

In your situation I would probably figure out the image size I wanted, and use the Crop Tool in Affinity Photo. There you can use the Resample mode, and specify the output size and DPI (probably 300) that you want. You will get a crop box that has the proper aspect ratio for the size you want, and you can drag a corner (maintaining that aspect ratio) to make it cover as much of the image as possible. You can then move it around to compose the image you want, and then Appy the crop.

[Alfred]

Start as you have been doing, without bothering to work out a scale factor.

2 hours ago, William Overington said:

So I start with a blank canvas of 2171 pixels by 1571 pixels at 300 dots per inch and I place the png image onto the canvas and then centre it on the page.

Drag the corners until the placed image fills the canvas, adjust its position to your liking and then export. The exported image will automatically be cropped to the size of the canvas.

[William Overington]

I always find these dragging to fit things awkward to do. I can manage most dragging.

I am very much happier when I can put numbers in boxes even if that means getting a pen and using the calculator  app to work out values and write them down.

But the issue I am concerned about is whether if I scale an image by some number other than an integer, will the print get some sort of moiré pattern sort of lines on it.

I suppose I am wondering how within the software, given a bitmap, how is the bitmap of an enlarged version calculated.

William

 

[Alfred]

34 minutes ago, William Overington said:

I am very much happier when I can put numbers in boxes even if that means getting a pen and using the calculator  app to work out values and write them down.

Affinity Designer will calculate values for you. For example, if you want the width to be seven fifths of the height, go to the Transform panel and put the desired height in the H box, and then put h*7/5 in the W box.

Affinity Designer Help: Expressions for field input

Quote

But the issue I am concerned about is whether if I scale an image by some number other than an integer, will the print get some sort of moiré pattern sort of lines on it.

Export to PDF and then inspect the result in a PDF viewer. What you see with the zoom factor set to 100% should be a fairly accurate representation of what the image will look like when printed.

[walt.farrell]

2 hours ago, William Overington said:

I am very much happier when I can put numbers in boxes even if that means getting a pen and using the calculator  app to work out values and write them down.

That's fine when the image you have matches the aspect ratio you need in the end. But when it doesn't, you will end up with extra white margins, or you'll need to enlarge and then crop.

 

[William Overington]

54 minutes ago, walt.farrell said:

That's fine when the image you have matches the aspect ratio you need in the end. But when it doesn't, you will end up with extra white margins, or you'll need to enlarge and then crop.

 

Well, I have found that exporting the jpg file needed to make the card does the cropping for me.

So I can have white margin on zero edges, one edge, two edges, three edges, or four edges depending, for each picture, upon whether I want all of the whole image at a smaller size or part of the image at a larger size.

One image 1366 by 768 that I have I doubled to 2732 by 1534 so place it by numbers on the blank canvas hard down at the lower edge and a bit overhanging on each side, so potentially a bit of white at the top, but as the sky is very light and by the fold of the card along the top long edge, the white space might be hardly noticeable.

I am attaching an image. I do not know if the forum software will reduce it in size.

The locomotive is running in reverse because there is no turntable available, so it must run in reverse when hauling a train in one of the two directions. For the return journey it ran forwards after doing a run round of the carriages after being uncoupled. Some locomotives on the line arrive forwards at Broadway then do the return trip in reverse. This locomotive, 35006, used to face the other way but was loaned elsewhere and when it returned it was decided to have it the other way round for a change so as to allow for different photograph opportunities when running forward.

William

 

[William Overington]

https://en.wikipedia.org/wiki/SR_Merchant_Navy_Class_35006_Peninsular_%26_Oriental_S._N._Co.

William

 

[Alfred]

9 hours ago, William Overington said:

Well, I have found that exporting the jpg file needed to make the card does the cropping for me.

Thank you for confirming what I said you would find:

14 hours ago, Alfred said:

Drag the corners until the placed image fills the canvas, adjust its position to your liking and then export. The exported image will automatically be cropped to the size of the canvas.

 

[William Overington]

39 minutes ago, Alfred said:

Thank you for confirming what I said you would find:

 

Well, it has long been the situation.

I used it in the first image, the one about the poem using language-independent glyphs, in the following thread.

 

 

That facility allowed me to have paint outside the canvas so as to get colour to the edges.

Here is a picture of what appears on screen.

 

 

 

When I exported the jpg file the cropping to the edge of the canvas was done automatically for me by the software as part of the exporting action.

William

 

[William Overington]

Here are four images, gathered earlier today.

The first one shows the coaches static after the train has arrived.

The second one shows the locomotive in forward motion going round the train.

The third one shows the locomotive stationary before departure.

The fourth one shows the train underway.

 

William

 

 

 

[William Overington]

Two more pictures, these gathered this afternoon, a little after 1500 and at 1513 respectively.

35006 going over the points.

35006 under way pulling the train.

 

 

 

William

 

[William Overington]

In the previous post I uploaded two images, but managed to include the first one twice in the post.

I have been looking at it and there seems to be an optical illusion of some sort as I found it difficult to realise that it is the same picture twice, as the rake of carriages do not appear parallel to each other in the two copies of the same picture.

Does anyone else observe the same effect please?

I use CTRL - several times to get the two images in full both together and the cariages seem to be at different angles.

William

 

[Alfred]

22 minutes ago, William Overington said:

Does anyone else observe the same effect please?

I do. I think it’s a trick of perspective, perhaps aided by the slight curvature of the track, but if you overlay a parallelogram it’s clear that the angle is the same.

[firstdefence]

24 minutes ago, William Overington said:

In the previous post I uploaded two images, but managed to include the first one twice in the post.

I have been looking at it and there seems to be an optical illusion of some sort as I found it difficult to realise that it is the same picture twice, as the rake of carriages do not appear parallel to each other in the two copies of the same picture.

Does anyone else observe the same effect please?

I use CTRL - several times to get the two images in full both together and the cariages seem to be at different angles.

William

 

In the bottom image of the duplicate images the carriages appear to be "more" horizontal.

[William Overington]

9 minutes ago, firstdefence said:

In the bottom image of the duplicate images the carriages appear to be "more" horizontal.

Yes, that is a good way to describe it.

William

 

[William Overington]

11 minutes ago, Alfred said:

I do. I think it’s a trick of perspective, perhaps aided by the slight curvature of the track, but if you overlay a parallelogram it’s clear that the angle is the same.

 

Though, apart from the vertical edges, the parallelogram does not look to have parallel edges! I am laughing out loud.

I have only just noticed the curve to which you refer. Yet is that white line along the edge of the platform really curved or could it be something to do with the lens of the webcam?

Wllliam

[R C-R]

51 minutes ago, firstdefence said:

In the bottom image of the duplicate images the carriages appear to be "more" horizontal.

FWIW, I downloaded the two images, opened one of them in AP, & added the second one aligned over it, & set the top one's blend mode to "Difference." The result was pure black, indicating to me both images are exactly the same.

[William Overington]

6 minutes ago, R C-R said:

FWIW, I downloaded the two images, opened one of them in AP, & added the second one aligned over it, & set the top one's blend mode to "Difference." The result was pure black, indicating to me both images are exactly the same.

That is worth knowing. Thank you.

William