Taken straight from the source for ADDING images:

  def valid_tv_episode_aspect_ratio?
    case aspect_ratio.round(2)
    when 1.33, 1.78
    else
      errors.add(:aspect_ratio, "is not within our acceptable ratio (1.33:1 or 1.78:1)")
    end
  end

  def valid_wide_aspect_ratio?
    errors.add(:aspect_ratio, "is not within our acceptable ratio (1.78:1)") if aspect_ratio && aspect_ratio.round(2) < 1.78 || aspect_ratio.round(2) > 1.78
  end

  def valid_profile_aspect_ratio?
    errors.add(:aspect_ratio, "is not within our acceptable ratio (1:1.5)") if aspect_ratio && aspect_ratio.round(2) > 0.67 || aspect_ratio.round(2) < 0.67
  end

  def valid_poster_aspect_ratio?
    errors.add(:aspect_ratio, "is not within our acceptable ratio (1:1.5)") if aspect_ratio && aspect_ratio.round(2) > 0.75
  end

So, what's happening there is I round the aspect ratio to 2 decimals and check if it's within the allowed thresholds. You'll see the thresholds for uploads is a bit more forgiving than the "valid aspect ratio" check that is showing on poster pages.

How do I calculate the extremes (smallest and biggest) of image aspect ratios that will get that green valid aspect ratio check mark?

Easiest thing to do is just make them exactly 1:1.78 or 1:1.5. But you can do the same as I do if you want to spend the extra time on it, divide height/width, round to 2 and see if they are within the valid thresholds.

However, that all sounds like more work than I would ever want to do. Photoshop lets you create preset crop ratios (I assume Gimp does as well) so once you have your presets added, you should never have to worry about this again. Your editing tool does the work for you.

I don't know how to do that with Gimp, and I'm perfectly comfortable and used to simply using a calculator to do it.

Yeah, the easiest thing to do is to round to the nearest pixel, but imo, some posters would benefit from even just one or a few pixels in width or height not being cropped.

I don't understand code, but if it's rounded to 2 decimals, am I correct in saying that a poster will get the green check mark if it's aspect ratio is between 1.495 and 1.505? (Any number within that range rounded to 2 decimals rounds to 1.5).

Not quite, the code above is just about adding images. I wasn't very clear before.

The "valid aspect ratio" check that is showing on image pages is different. It's a check with essentially no forgiveness.

For posters, it's width/height, rounded to 2 decimals.

1000/1500
= 0.666666666666667

0.666666666666667.round(2)
0.67

So is 0.67 = 0.67? Yes, valid aspect ratio. Any other number? Invalid.

Here's 2 links that talk about saving preset crop aspect ratios in Gimp:

• http://shallowsky.com/blog/gimp/gimp-tool-presets.html
• https://www.reddit.com/r/GIMP/comments/3ylgt4/custom_preset_aspect_ratios/

So if there's essentially no forgiveness then how come an image like this has the green check mark (as shown here)?

1) That image's aspect ratio: 1334/2000 = 0.667.

2) That image's aspect ratio if width was reduced by one pixel: 1333/2000 = 0.6665.

Which one is closer to 1000/1500 = 0.0.666666666666667?

2).

So if that image gets the green check mark, (when it isn't the closest it could possibly be to the ideal aspect ratio) that indicates to me there's a range of aspect ratios that gets the green check mark.

Or do you mean it's supposed to be the closest to 1000/1500 rounded to 2 decimal points? i.e. the closest to 0.67 rather than the closest to 0.0.666666666666667?

@tmdb24407783 said:

So if there's essentially no forgiveness then how come an image like this has the green check mark (as shown here)?

1) That image's aspect ratio: 1334/2000 = 0.667.

2.5.1 :006 > (1334.0/2000.0).round(2)
 => 0.67

It rounds to 0.67, so yes,

2) That image's aspect ratio if width was reduced by one pixel: 1333/2000 = 0.6665.

2.5.1 :007 > (1333.0/2000.0).round(2)
 => 0.67

Also rounds to 0.67, so

It would take to dropping the width to 1329 to be invalid:

2.5.1 :006 > (1334.0/2000.0).round(2)
 => 0.67
2.5.1 :007 > (1333.0/2000.0).round(2)
 => 0.67
2.5.1 :008 > (1332.0/2000.0).round(2)
 => 0.67
2.5.1 :009 > (1331.0/2000.0).round(2)
 => 0.67
2.5.1 :010 > (1330.0/2000.0).round(2)
 => 0.67
2.5.1 :011 > (1329.0/2000.0).round(2)
 => 0.66

3). So if that image gets the green check mark, (when it isn't the closest it could possibly be to the ideal aspect ratio) that indicates to me there's a range of aspect ratios that gets the green check mark.

Or do you mean it's supposed to be the closest to 1000/1500 rounded to 2 decimal points?

I suspect the above demonstration cleared this up, divide the width and height, round to 2 decimals and if they don't equal 0.67 then it's invalid.

Oh, ok! So the range is between 0.665 to 0.675 for posters, and 1.775 to 1.785 for backdrops! Thanks!

Yes, exactly.