libvips
diff --git a/‎_posts/2025-03-20-introduction-to-nip4.md
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diff --git a/‎assets/images/nip4-scale.png
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@@ -10,7 +10,8 @@ If you used nip2, there's a [nip4 for nip2
 users](https://www.libvips.org/2025/03/12/nip4-for-nip2-users.html) post
 which runs though the main differences.
 
-I'll write a "nip4 for nerds" post introducing nip4's programming language.
+I'll write a "nip4 for nerds" post next week introducing nip4's programming
+language.
 
 ## Background
 
@@ -51,27 +52,27 @@ cells in the workspace and watch pixels change as you edit the formula.
 
 The whole systems is lazy and demand-driven. You can load enormous images
 (many 100s of gigabytes) and manipulate them interactively, since only the
-pixels need to update the screen actually get processed. When you do a final
+pixels needed to update the screen actually get processed. When you do a final
 save operation, it will take a while, of course.
 
 nip4 comes with a separate program called `nip4-batch`. This is a batch-mode
 processor that can load nip4 workspace files and execute them on a set of
 inputs. You can use to apply a workspace you've developed in nip4 to a big
-library of data.
+collection of images.
 
 ## The main window
 
 When you start nip4, it looks something like this. I've loaded a test image
 (drag one in, use the folder button at the top left, or start nip4 from the
-command-line with `nip4 nina.jpg`):
+command-line with `nip4 my-great-image.jpg`):
 
 ![nip4]({{ site.baseurl }}/assets/images/nip4-main-window.png)
 
 `A` is the current column, `A1` is a row for the image you loaded, this is all
 in `tab1`. The thing down the left is the set of loaded toolkits. 
 
 The toolkit menu contains around 300 useful operations, and you can make more
-yourself. You can click around to move in and out of sub-toolkits, or you can
+yourself. You can click to move in and out of toolkits, or you can
 click in the magnifying glass at the top and search for tools by keyword.
 
 If you select Filter > Photographic Negative you'll see:
@@ -82,7 +83,7 @@ Most tools take one argument, and they are applied to the bottom row
 in the current column. If you want to apply a tool to a row other than the
 bottom one, select it first by clicking on the row label.
 
-If you open up the row by clicking on the `V` down button next to A2,
+If you open up `A2` by clicking on the `V` down button next to the label,
 you'll see the cell formula:
 
 ![nip4]({{ site.baseurl }}/assets/images/nip4-formula.png)
@@ -99,21 +100,22 @@ bar to get back to the start position, then click Widgets > Scale to add a
 scale widget called `A3` to the workspace. Now edit the formula to be
 `A3 - A1` and try dragging the slider. 
 
-![nip4]({{ site.baseurl }}/assets/images/nip4-scale.png)
-
 It looks a bit awkward with the result row `A2` positioned before the scale.
 You can reorder columns by dragging on the row label. 
 
+![nip4]({{ site.baseurl }}/assets/images/nip4-scale.png)
+
 You can enter new formula in the text box at the bottom of the column.
 Solarisation is a photographic technique where bright areas of the image
 become inverted. 
 
-This is easy to write as a formula: first, duplicate column `A` by
-right-clicking on the column title and selecting Duplicate from the menu. nip4
-does not have an undo operation, instead it has fast and easy duplicate,
-merge and delete. If you make a copy of `A` before you start changing it,
-you can't lose any of your current work. Right-click on `B3` and selecte
-Delete, so you have:
+This is easy to write as a formula.  nip4 does not have an undo operation,
+instead it has fast and easy duplicate, merge and delete. If you make a
+copy of column `A` before you start changing it, you can't lose any of your
+current work.
+
+Duplicate column `A` by right-clicking on the column title and selecting
+Duplicate from the menu.  Right-click on `B3` and select Delete, so you have:
 
 ![nip4]({{ site.baseurl }}/assets/images/nip4-duplicate.png)
 
@@ -123,12 +125,12 @@ Now in the text box at the bottom of column `B`, enter the formula:
 if B1 < B2 then 255 * B1 / B2 else 255 * (255 - B1) / (255 - B2)
 ```
 
-And try dragging the slider again. Hopefully you'll see a solarised image.
+And try dragging scale `B2`. Hopefully you'll see a solarised image.
 This operation is also in the standard toolkits, next to Photographic
 Negative.
 
 If you double-click on an image thumbnail, you'll open an image view window.
-These are all live, so as you drag sliders, they'll all update. You can zoom
+These are all live, so as you drag scales, they'll all update. You can zoom
 in and watch the values of individual pixels change as you edit formula.
 
 ![nip4]({{ site.baseurl }}/assets/images/nip4-solarise.png)
@@ -167,10 +169,10 @@ The nip4 image view window has a lot of useful shortcuts.
 * F11 fullscreen
 
 If you select View > Display Control Bar, some widgets appear at the bottom.
-They let you flip pages, animation frames, set a scale and offset for each
-pixel (handy for scientific images), and a burger menu gives a set of useful
-visualisation options, such as false colour, log scale, and colour
-management.
+They let you flip pages, move to animation frames, set a scale and offset
+for each pixel (handy for scientific images), and a burger menu gives
+a set of useful visualisation options such as false colour, log scale,
+and colour management.
 
 ![nip4]({{ site.baseurl }}/assets/images/nip4-image-window.png)