The Target Impact Analyser measures your shooting groups from a photo of the target. You open the photo, tell the app the scale, let it find the bullet holes, correct anything it got wrong, and save the result. A photo can hold several groups (a card with many small diagrams, or several series on one target): each group is measured on its own, and the photo gets the mean and spread of its groups. Over time the saved records give you the average group size per weapon, with its standard deviation.
Requirements: Windows 10/11 and Python 3.10 or newer (https://www.python.org/downloads/, tick Add python.exe to PATH during installation).
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Open PowerShell in the application folder (right-click the folder, Open in Terminal).
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Run the setup once:
.\setup.ps1
It creates a private Python environment (
.venv) and downloads the libraries. -
Start the application:
.\run.ps1
run.ps1runs the setup by itself if.venvis missing.
If PowerShell refuses to run scripts, allow local scripts once:
Set-ExecutionPolicy -Scope CurrentUser RemoteSignedYour data is stored in the file targets.db next to the scripts, and a copy of every
saved photo goes to the images\ folder next to it (JPEG, reduced to 2500 pixels on
the longest side). Back up the database file and the images\ folder together. To
use a different database file: .\run.ps1 C:\path\to\other.db (its images\ folder
is created next to that file).
The detector works on any phone photo, but these habits make it reliable:
- Shoot the target flat and from the front, with the camera parallel to the paper. A strong angle distorts distances.
- Even light without hard shadows across the target (no phone shadow, no window glare). Soft shadows are tolerated.
- Keep the whole target in the frame with some paper margin around it.
- Accepted formats: JPEG, JPG, PNG, HEIC/HEIF (iPhone), BMP, TIFF, WebP. The photo is rotated automatically according to the phone's orientation data.
The window has three tabs: Analyse (blue), Records & averages (green) and Parameters (orange). Click a tab name to open it; the open tab is shown in its full colour, the others in a light shade.
The Analyse tab has three areas:
| Area | Content |
|---|---|
| Left column | The workflow buttons: open image, scale tools, detection parameters, manual correction tools. |
| Centre | The photo, with the zoom bar above it. Click on it when a tool is active. |
| Right column | The group list with its buttons, the measurements of the selected group, the summary of the photo, the display unit and the save form. |
Zoom in to place the scale points or the missing shots precisely, especially on a card with many small diagrams.
| Action | How |
|---|---|
| Zoom in at a point | Ctrl + click on it, or turn the mouse wheel forwards over it. |
| Zoom out | Ctrl + right-click (or Ctrl + Shift + click), or turn the wheel backwards. |
| Choose the zoom level | Drag the slider in the zoom bar, or use the − and + buttons (or the − and + keys after clicking the photo). |
| See the whole photo | Fit (or the 0 key). |
| Zoom on one group | Select it in the group list and press Zoom to group, or double-click its row. |
| Move the photo | Drag with the right mouse button (works whatever tool is active), or with the left button when no tool is active. |
The zoom level appears in the bar (fit, ×2.5, … up to ×40). The impact circles grow with the zoom, so they keep the same size relative to the holes (this can be switched off in the Parameters tab). Lines keep their width. Ctrl + click never adds or removes a shot, even with a tool active. Opening another photo returns to fit.
Click 1. Open image… and choose the photo. The file name and pixel size appear in the status line at the bottom right.
The app needs to know how many pixels make a centimetre. Two ways:
Measure 2 points (recommended when you know a real distance)
- Click Measure 2 points.
- Click two points on the photo whose real distance you know, for example the two edges of the black circle, or two ring lines, or a ruler laid on the target. A yellow line joins the points.
- In the dialog, type the real distance and choose cm or inch.
Auto: from outer black circle
The app finds the outer edge of the black part of the target. Type its real diameter (the default is 20 cm, the black disc of a 25 m precision pistol target). Check the green circle drawn on the photo: if it does not follow the black edge, use the 2-point method instead.
The scale label turns green once the scale is set. Set the scale before analysing: the app uses it to tell single holes from torn multi-shot regions.
Optionally type the number of Shots fired. Then click Analyse impacts.
Each detected shot is drawn as a numbered yellow circle. A dashed rectangle in the group's colour shows each group's extent and a cross marks its centre. Detected torn regions that contain several shots are split into several points. The colours, line styles and widths can be changed in the Parameters tab (section 6).
If the photo shows several target diagrams (a card of 10 or 25 small targets), the app finds every black circle and makes one group per diagram: the circles are drawn in the group colours with their names (G1, G2, … in reading order) and every shot is assigned to the nearest diagram. Diagrams without any shot appear greyed in the group list. A photo with a single target gives a single group G1.
Automatic detection is good but not perfect. Fix it with the click tools:
- Add impact (click): click on each hole the app missed. These are drawn with a dashed outline. The tool stays active until you choose another one.
- Remove impact (click): click on a wrong circle to delete it.
- Clear all impacts: start again from zero (useful if you prefer to mark all shots by hand). The groups are kept.
- Move impact to selected group (click): select the destination group in the list, then click the shots to move there (for example a shot that landed between two diagrams and was assigned to the wrong one).
Typical things to correct:
- A big torn hole whose shot count was estimated wrong (remove or add points).
- Coloured pasters or marker pen marks taken for holes.
- Dirt, folds or a strong shadow edge taken for holes.
- A hole on the white paper far outside the rings that was missed.
The measurements update immediately after every correction.
The Groups list at the top right shows every group with its number of shots and its width, height and diameter. Click a row to select a group: on the photo it gets a thick red circle and a red box, drawn above the other groups; its values appear under Selected group, and the Add impact and Move impact tools work on it.
- New: creates a group (you can name it; the default is the next G number) and switches to Add impact so you can click its shots right away. Use it when one target carries several series shot one after the other, or when the automatic grouping missed a diagram.
- Rename: changes the name of the selected group (for example the cell number printed on the card).
- Delete: removes the selected group and its shots after confirmation. To keep the shots, move them to another group first with Move impact to selected group.
- Auto-group: target circles: redoes the automatic grouping by printed circle on the current shots (after you added shots by hand, for example). Needs at least two circles in the photo.
- Auto-group: distance: groups the shots by proximity. Shots closer than the distance you type (default 5 cm) end up in the same group. Use it for several series on a plain target without printed circles; pick a distance smaller than the gap between the series and larger than the spread inside one.
Empty groups are shown in grey, are not measured and are not saved.
The right column shows, in the chosen display unit (cm or inch), for the selected group:
| Value | Meaning |
|---|---|
| Shots | Number of impact points in the group. |
| Width | Horizontal spread, centre of the leftmost hole to centre of the rightmost. |
| Height | Vertical spread, centre to centre. |
| Diameter (extreme spread) | Largest centre-to-centre distance between two holes. This is the usual "group size". |
All values are centre to centre. To get an edge-to-edge group size, add one bullet diameter to the diameter value.
Under This image you get the same figures over all the groups of the photo that contain shots: number of groups and total shots, then the mean ± standard deviation of the width, height and diameter, and the P90 diameter (90 % of the groups are at or below it). With a single group the means equal the group values and the deviations are 0.
Fill in the form (date, weapon, distance, ammunition, notes) and click
Save to database. One record is saved for the photo with all its groups and shots;
the status line confirms the record number, the number of groups and the name of the
photo copy stored in images\. The original photo is no longer needed afterwards. The
weapon name is used later for filtering, so write it the same way every time (for
example 45 or SP01).
Every record gets its own photo copy, named with the date and time, the record number
and the original name (for example 20261030_101530_r12_IMG_5862.jpg). Saving the
same photo again, or another photo with the same file name, never overwrites anything.
The app asks first: Record(s) #10, #11 were already saved from a photo named
'IMG_5862.jpeg'. Save another record? Answer No if you saved it already, since a
duplicate counts twice in the averages. Answer Yes for a re-measured target or a
different photo that happens to share the name. A record reopened with Load record
keeps its original photo name.
The second tab lists every saved record (one row per photo) with the original photo file name, its number of groups, total shots and the mean width, height and diameter of its groups, in the current display unit.
- Weapon filter: show only one weapon. Leave empty for all.
- Refresh: reload the list (it also refreshes when you open the tab).
- Average of selection: select one or more rows (Ctrl-click or Shift-click) and press the button. The box below shows, for width, height, diameter and shots per group, the mean ± sample standard deviation over all the groups of the selected records, in both cm and inch side by side (whatever the display unit). A card with 25 groups therefore counts 25 times, a single-group photo once. The line Diameter P90 is the 90th percentile of the group diameters: 90 % of the groups have a diameter at or below this value, which makes it a good "what I can count on" figure. Selecting one record gives the statistics of that photo's groups.
- Average of all listed: the same over every row currently listed (so with a weapon filter, the average for that weapon).
- Load record: select exactly one row and reopen the stored photo copy with its groups, impacts, scale and form fields, for checking or re-measuring.
- Delete selected: removes the selected records after confirmation, together with
their stored photo copies in
images\when no other record uses them. This cannot be undone.
The Parameters tab sets how impacts and groups are drawn on the photo. Each line has a colour, a Group colour tick box, a line style (solid, dashed, dotted, dash-dot) and a width in screen pixels:
| Element | Default |
|---|---|
| Impact circle | yellow, solid, 2 |
| Impact added by hand | yellow, dashed, 2 |
| Group: target circle | group colour, dashed, 1 |
| Group: box and centre cross | group colour, dashed, 1 |
| Selected group: target circle | red, solid, 4 |
| Selected group: box and centre cross | red, solid, 2 |
Click a colour square to choose a colour. Tick Group colour to use each group's own colour from the palette (blue, green, magenta, cyan, …) instead. Impact circle radius sets the size of the impact circles when the whole photo is shown (default 10). With Impact circles grow with the zoom ticked (default) they are enlarged with the zoom and keep the same size on the photo; untick it to keep them the same size on screen at any zoom. The preview on the right and the photo update at once. The settings are saved in the database and come back at the next start; Reset to defaults restores the table above.
The defaults work for the target styles the app was tuned on: targets with a solid black disc (25 m precision pistol), ring targets with a white centre (10 m air rifle / pistol cards) and cards of 25 small ring diagrams (.22 "Hunter"), on grey or wooden backing. Change a parameter and click Analyse impacts again to see its effect.
| Parameter | Default | When to change it |
|---|---|---|
| Hole max brightness (% of paper) | 84 | Holes appear as grey or brown backing darker than the paper. Raise it (e.g. 88) if light-grey holes are missed. Lower it (e.g. 78) if shadows or dirt are detected as holes. |
| Colour saturation (0-255) | 95 | Wood backing is detected by its orange colour. Lower it if brown holes are missed; raise it if warm-lit paper or coloured pasters are detected. |
| Open kernel (px) | 11 | Removes ring lines, digits and print edges. Raise it if lines or digits are detected; lower it if small holes disappear. |
| Min area (px²) | 150 | Smaller spots are ignored. Raise it to drop dust and small specks. |
| Hole core Ø (mm) | 4.0 | The size of the clean part of one hole on your targets. With the scale set, this tells single holes from torn multi-shot regions. For .45 ACP on paper the visible core is about 4 mm; air rifle pellets about 4.5 mm. |
| Shots fired | empty | Type the real number when you know it: the torn regions are then split into exactly the missing number of shots. |
| Symptom | What to do |
|---|---|
| No black circle found when using the auto scale | Use Measure 2 points instead. |
| Measurements show "- (set scale)" | Set the scale (step 4.2). |
| Many false circles along a shadow edge | Retake the photo without the hard shadow, or lower Hole max brightness, or remove them with the Remove tool. |
| Every hole is split into several points | Set the scale before analysing, and check Hole core Ø. Or type Shots fired. |
| Holes on the white paper outside the rings are missed on a solid-disc target | Add them with Add impact. |
| Holes showing a nearly black backing (black board, very dark wood in a shadow) are missed | They cannot be told from the print by colour. Select the group and add them with Add impact. |
| A card gives fewer groups than diagrams | A circle broken by the grid line or by writing is not found. Press New to create the missing group and click its shots, or move them with Move impact to selected group. |
| A shot between two diagrams went to the wrong group | Select the right group and use Move impact to selected group. |
Cannot open a .heic file |
Run .\setup.ps1 again; it installs the pillow-heif package. |
| The app does not start | Run .\setup.ps1 and read its last lines; it checks every library. |